ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Ultrastructure  (1,615)
  • Column liquid chromatography  (1,216)
  • Springer  (2,831)
  • 1
    Electronic Resource
    Electronic Resource
    Glomus claroideum forms an arbuscular mycorrhiza-like symbiosis with the hornwort Anthoceros punctatus (2000)
    Springer
    Mycorrhiza 10 (2000), S. 15-21 
    Details
    ISSN: 1432-1890
    Keywords: Anthoceros punctatus ; Arbuscular mycorrhiza ; Bryophytes ; Glomus ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Glomus claroideum (Schenck & Smith emend. Walker & Vestberg) were investigated for ability to form arbuscular mycorrhiza-like symbioses with the hornwort Anthoceros punctatus (L.). Spores were transferred to a cellulose acetate filter on water agar and a small portion of an Anthoceros thallus was placed directly upon the spores. Light-microscope observations 20 days after inoculation revealed branched hyphae growing within the thallus. After 45 days, arbuscules and vesicles were studied by light- and electron-microscopy. After 60 days in water agar culture, the colonised Anthoceros thalli were transferred to a low-nutrient medium agar. Hyphae spread in the agar and newly formed spores were observed 5 weeks after the transfer. After 4 months, about 1000 spores were formed in each Petri dish. This is the first report of an experimentally established arbuscular mycorrhiza-like symbiosis between an identified fungus belonging to the Glomales and a bryophyte.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005720050282
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The need for speed. II. Myelin in calanoid copepods (2000)
    Springer
    Journal of comparative physiology 186 (2000), S. 347-357 
    Details
    ISSN: 1432-1351
    Keywords: Key words Crustacean ; Sensorimotor ; Ultrastructure ; Multilamellar sheath ; Myelinated axons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Speed of nerve impulse conduction is greatly increased by myelin, a multi-layered membranous sheath surrounding axons. Myelinated axons are ubiquitous among the vertebrates, but relatively rare among invertebrates. Electron microscopy of calanoid copepods using rapid cryofixation techniques revealed the widespread presence of myelinated axons. Myelin sheaths of up to 60 layers were found around both sensory and motor axons of the first antenna and interneurons of the ventral nerve cord. Except at nodes, individual lamellae appeared to be continuous and circular, without seams, as opposed to the spiral structure of vertebrate and annelid myelin. The highly organized myelin was characterized by the complete exclusion of cytoplasm from the intracellular spaces of the cell generating it. In regions of compaction, extracytoplasmic space was also eliminated. Focal or fenestration nodes, rather than circumferential ones, were locally common. Myelin lamellae terminated in stepwise fashion at these nodes, appearing to fuse with the axolemma or adjacent myelin lamellae. As with vertebrate myelin, copepod sheaths are designed to minimize both resistive and capacitive current flow through the internodal membrane, greatly speeding nerve impulse conduction. Copepod myelin differs from that of any other group described, while sharing features of every group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003590050435
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Structural changes during early embryogenesis in wheat pollen (2000)
    Springer
    Protoplasma 211 (2000), S. 94-102 
    Details
    ISSN: 1615-6102
    Keywords: Androgenesis ; Embryogenesis ; Microspore culture ; Pollen ; Ultrastructure ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have made a detailed cytological examination of the development of wheat embryoids, monitoring their initial divisions from two to ten cells by both light and electron microscopy. According to our observations the first embryogenic division is symmetrical. After the androgenesis induction treatment, there is a decrease in ribosome population with cells that have inactive nucleoli made up almost exclusively of a dense fibrillar component. This population is restored after initial embryogenic divisions. During the initial divisions the embryogenic pollen grains do not appear to change in size and the pollen wall remains intact. The exine undergoes no modification but the intine thickens, and we have observed that the thickness of the intine can be used as a cytological marker of androgenesis. The walls separating the cells obtained after embryogenic division contained numerous plasmodesmata. The beginnings of embryo polarization and cell differentiation could be made out in the very early pollen embryoids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279902
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Effects of glutathione on thiol redox systems, chromosomal aberrations, and the ultrastructure of meristematic root cells ofPicea abies (L.) Karst. (2000)
    Springer
    Protoplasma 212 (2000), S. 227-235 
    Details
    ISSN: 1615-6102
    Keywords: Glutathione ; Root ; Chromosomal aberration ; Ultrastructure ; Picea abies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Young spruce seedlings (Picea abies [L.] Karst.) grown in hydroponic culture were exposed to three different concentrations (50,100, and 500 μM) of reduced glutathione for 24 h. These physiologically relevant concentrations of glutathione had a multiple effect on the investigated tissue. Feeding of glutathione to roots increased the concentrations of thiols (glutathione, cysteine, and γ-glutamyl-cysteine) in roots, decreased the rate of cell divisions, induced mitotic abnormalities, and affected the cell ultrastructure. Electron micrographs showed effects such as advanced vacuolation, dilated rough-endoplasmic-reticulum cisternae, and separations of the plasma membrane from the cell wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282923
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ultrastructure and anatomy of nematode-induced syncytia in roots of susceptible and resistant sugar beet (2000)
    Springer
    Protoplasma 211 (2000), S. 39-50 
    Details
    ISSN: 1615-6102
    Keywords: Beta vulgaris ; Cyst nematodes ; Histology ; Resistance mechanism ; Syncytium ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Using susceptible and resistant sugar beet lines, comparative analyses of root histology and ultrastructure were made during invasion by nematodes and the induction and formation of specific feeding structures (syncytia).The resistant line carried the resistance geneHs1pro−1.Nematodes were able to invade and induce functional syncytia in roots of resistant and susceptible lines. However, syncytia in resistant roots were smaller and less hypertrophied. The vacuolar system of syncytia in susceptible plants contained many small vacuoles. In resistant plants vacuoles were larger but less numerous. Smooth endoplasmic reticulum prevailed in syncytial protoplasts of susceptible plants, whereas almost only rough endoplasmic reticulum occurred in syncytia in resistant plants. The most conspicuous and hitherto undescribed trait of syncytia in resistant roots was the initial appearance of loose, and later compact, aggregations of the endomembrane system which composed most of the endoplasmicreticulum system of syncytia at later stages. Syncytia in resistant plants usually degraded before the nematodes reached their adult stage. The appearance of membrane aggregations and the other resistance-specific features are discussed in relation to their possible effects on syncytium function and role in nematode resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279898
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Effect of osmotic stress on tolerance of air-drying and cryopreservation ofArabidopsis thaliana suspension cells (2000)
    Springer
    Protoplasma 214 (2000), S. 227-243 
    Details
    ISSN: 1615-6102
    Keywords: Arabidopsis thaliana ; Cryopreservation ; Dehydration ; Thermal analysis ; Sucrose ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Arabidopsis thaliana suspension cells were preserved in liquid nitrogen for over three years, using embedding of cells in calcium-alginate prior to subculture in sucrose-enriched medium, air-drying, and direct quenching in liquid nitrogen. Survival of cells reached 34%, yielding regrowth at the surface of all cryopreserved beads in less than 7 days. Following pretreatment and dehydration, the water content dropped from 2300% to 34% with respect to dry weight. Differential scanning calorimetry showed that glass transition occurred on cooling, followed by a slight crystallization event on rewarming. The survival of cells was independent of the cooling rate. The tolerance of the acute dehydration step increased progressively with sucrose pretreatment duration, indicating the requirement for adaptative cellular alterations. Ultrastructural studies revealed several changes in cells after sucrose pretreatment prolonged from 1 to 7 days: reversal of the initially plasmolyzed state, microvacuolation, numerous autophagic structures, scarcity of ribosomes, increase in number and size of starch grains. No cell division seemed to occur during this period. After air-drying and after a freeze-thaw cycle, followed by 24 h rehydration, regenerating cells had recovered a high level of ultrastructural organization and contained numerous polysomes suggesting an intense metabolic activity. Trehalose, a cryoprotective disaccharide not considered to be a metabolic substrate, yielded only 70% regrowth after freezing. Biochemical analysis showed that soluble sugars accumulated during the pretreatment, essentially sucrose or trehalose; the monosaccharide content also increased. In the light of these results, the action of sucrose in inducing freezing tolerance is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279067
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Larva-adult relationships in an ancestral dipteran: A re-examination of sensillar pathways across the antenna and leg anlagen of Chaoborus crystallinus (DeGeer, 1776; Chaoboridae) (1999)
    Springer
    Development genes and evolution 209 (1999), S. 103-112 
    Details
    ISSN: 1432-041X
    Keywords: Key words Imaginal disc ; Axonal trajectories ; Ultrastructure ; Chaoborus (Insecta ; Diptera)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In one of his classical studies on insect metamorphosis, Weismann compared the imaginal anlagen of the ancestral phantom midge, Chaoborus, with those of advanced brachycerans. We have expanded his findings on the relationships between larval and imaginal organs using electron microscopy and cobalt backfilling of the antenna and leg anlagen and the axonal trajectories of corresponding larval sensilla. We show that both primordia are confluent with the larval antennae and ”leg” sensilla (an ancestral Keilin organ), respectively. These fully developed larval organs represent the distal tips of the imaginal anlagen rather than separate cell clusters. The axons of the larval antenna and leg sensilla project across the corresponding anlagen to their target neuromeres within the central nervous system (CNS). Within the discs, nerves composed of these larval axons, developing afferent fibres and efferences ascending from the CNS are found. Both the structure of the primordia and the axonal trajectories thus relate the situation found in advanced brachycerans with that seen in more ancestral insects. In addition, the larval antennae, legs, wings and even the eyes possess very similar afferent pioneer trajectories supporting the idea that the described pattern is generally used in the ontogeny of sensory systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050232
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a Clostridium sp. with cinnamoyl esterase activity and unusual cell envelope ultrastructure (1999)
    Springer
    Archives of microbiology 172 (1999), S. 139-149 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsClostridium xylanolyticum ; Cinnamic acid ; Esterase ; Lignocellulose ; Sporogenesis ; Ultrastructure ; Cell envelope
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microorganisms that hydrolyse the ester linkages between phenolic acids and polysaccharides in plant cell walls are potential sources of enzymes for the degradation of lignocellulosic waste. An anaerobic, mesophilic, spore-forming, xylanolytic bacterium with high hydroxy cinnamic acid esterase activity was isolated from the gut of the grass-eating termite Tumilitermes pastinator. The bacterium was motile and rod-shaped, stained gram-positive, had an eight-layered cell envelope, and formed endospores. Phylogenetic analysis based on 16S rRNA indicated that the bacterium is closely related to Clostridium xylanolyticum and is grouped with polysaccharolytic strains of clostridia. A wide range of carbohydrates were fermented, and growth was stimulated by either xylan or cellobiose as substrates. The bacterium hydrolysed and then hydrogenated the hydroxy cinnamic acids (ferulic and p-coumaric acids), which are esterified to arabinoxylan in plant cell walls. Three cytoplasmic enzymes with hydroxy cinnamic acid esterase activity were identified using non-denaturing gel electrophoresis. This bacterium possesses an unusual multilayered cell envelope in which both leaflets of the cytoplasmic membrane, the peptidoglycan layer and the S layer are clearly discernible. The fate of all these components was easily followed throughout the endospore formation process. The peptidoglycan component persisted during the entire morphogenesis. It was seen to enter the septum and to pass with the engulfing membranes to surround the prespore. It eventually expanded to form the cortex, verification for the peptidoglycan origin of the cortex. Sporogenic vesicles, which are derived from the cell wall peptidoglycan, were associated with the engulfment process. Spore coat fragments appeared early, in stage II, though spore coat formation was not complete until after cortex formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050753
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    The effect of pH on the high pH anion-exchange chromatography elution of monosaccharides (1999)
    Springer
    Chromatographia 49 (1999), S. 699-702 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; High ph elvents ; Monosaccharides ; Carbopac PA-100
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have studied the elution behaviour of six common monosaccharides, fucose, galactosamine, glucosamine, galactose, glucose and mannose, on the CarboPac PA-100 column. The relative elution positions of galactose, glucose and mannose were dependent on the sodium hydroxide concentrations, a phenomenon which was likely to be the result of differential ionisation of the hydroxyl groups at ring positions two and four. The optimal resolution of the monosaccharides studied was achieved by elution with 30 mM sodium hydroxide with no appreciable loss in sensitivity at this low concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466915
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    High performance liquid chromatography method for the determination of meropenem in human plasma (1999)
    Springer
    Chromatographia 49 (1999), S. 253-255 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Meropenem in human plasma ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes an HPLC method for the determination of meropenem in human plasma. The method uses solid phase extraction (SPE) of the samples and has good sensitivity, precision and accuracy. The limit of quantification in plasma samples is 0.02 μg mL−1. Calibration curves were linear over a large dynamic range, namely within 0.02–50 μg mL−1. The method was applied to the determination of meropenem levels in patients receiving meropenem, as a single dose or at steady state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467552
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 11
    Electronic Resource
    Electronic Resource
    FMOC-Cl as derivatizing agent for the analysis of amino acids and dipeptides by the absolute analysis method (1999)
    Springer
    Chromatographia 49 (1999), S. 317-320 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amino acids ; FMOC derivatives ; Oligopeptides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary One classical method for quantitation of amino acids in proteins is hydrolysis of the proteins and determination of the free amino acids. Although the drastic experimental conditions necessary for complete hydrolysis always cause degradation of some of the amino acids, if mild hydrolysis conditions are used, a mixture of amino acids and oligopeptides is obtained. If these conditions are adequately tuned, the oligopeptides are almost exclusively dipeptides. For this reason we have initiated a study to find a derivatizing agent suitable for the analysis of amino acids and dipeptides by an absolute method of quantitation already tested for amino acids. FMOC-Cl was found to be a suitable derivatizing agent for this purpose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467563
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Potentiometric detection of monovalent anions separated by ion chromatography using all solid-state contact PVC matrix membrane electrode (1999)
    Springer
    Chromatographia 49 (1999), S. 338-342 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Monovalent anions determination ; Potentiometric detection ; Ion selective PVC-matrix electrode
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An all solid-state contact tubular PVC-matrix membrane electrode has been applied for potentiometric detection of inorganic and organic monovalent anions using phosphate and hydrogen phosphate eluents at low concentrations. This is a “monovalent detection method” as the selectivity of the electrode towards monovalent anions results in some other anions being undetected unless the concentration of those other anions is higher than 10−3 mol dm−3 in the sample solution injected. It takes only eight minutes to complete the separation with a good resolution. Theoretical and practical considerations are discussed, and in particular, sensitivity, linearity, detection limit and dynamic behaviour are presented. The use of an all solid-state contact bromide-selective electrode as a detector offers so far the best simultaneous sensitivity toward all anions when compared with other detection methods. Determination of Cl− and NO3 − ions in river, rain and drinking water samples without any further sample preconcentration has been successfully achieved. The detection limit is sub-ppb for most of anions in a 20 μL injection volume.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467567
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    A system for predicting the retentions of O-alkyl, n-(1-methylthioethylideneamino) phosphoramidates on RP-HPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 444-448 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; O-alkyl, O-(1-methylthioethylideneamino) phosphoramidates ; Quantitative structure-retention relationship (QSRR) ; Reversed-phase LC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By using factor analysis, cluster analysis and multiple linear regression methods, two parameters, FHF and ECCR, were selected from eight solute-related structure parameters as showing the best correlation with retention data. The relationship between the retention data (k) and these two structure parameters were established for ten O-alkyl, O-(1-methylthioethylideneamino) phosphoramidate compounds under the experimental conditions studied. Retention data (k) for six other compounds that have a high correlation with structure parameters were predicted using these QSRR equations. The system was evaluated by comparing the experimentalk values with the predicted ones. Good agreement was obtained between the experimental and predictedk values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467621
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 14
    Electronic Resource
    Electronic Resource
    Determination of flupoxam residues in soil by high performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 535-538 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Herbicides in soil ; Flupoxam
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography with UV detection was used to determine the residues of flupoxam (a new herbicide) in soils. Soil samples were extracted with aqueous methanol. The soil extracts were cleaned up and concentrated using two solid phase extraction columns: a polymeric stationary phase based on a polystyrene-divinylbenzene resin (Lichrolut EN) and alumina. Recovery experiments were performed at ppb levels in spiked soil samples. The recovery was 76±1.7% for flupoxam in the range 5–100 μg kg−1 of soil. Limit of determination was 3 μg kg−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467754
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Analysis of doxorubicin in cell culture media and human plasma using solid phase extraction and HPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 557-561 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Doxorubicin ; Cell culture media ; Human plasma ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Doxorubicin is an antineoplastic antibiotic isolated fromStreptomyces peucetius var.cesius clinically used in the treatment of tumors such as lung or breast, Hodgkin's disease and various types of leukemias. The main goal of this study was to develop a simple and sensitive HPLC method with fluorescence detection for the quantitation of doxorubicin in cell culture media collected during an in vitro studies and in human plasma. Solid phase extraction (C2 silica) was applied. The experiment established five-point standard curve (1 ng mL−1 to 100 ng mL−1). The standard curves prepared in blank cell tissue media were linear over the range of doxorubicin assayed and had a mean correlation coefficient of 0.9973±9.43×10−4 and slope 0.02545±1.85×10−3. The standard curves prepared in human plasma were linear and had mean correlation coefficient of 0.997 and slope 0.01885±5.19×10−4. The limit of quantitation for doxorubicin in both specimens was arbitrarily established to be 1 ng mL−1. Intra-day variabilities were determined using 3–4 replicates of control solutions of doxorubicin (3 ng mL−1 and 30 ng mL−1) in blank plasma and cell culture media. Inter-day variabilities were determined over a four day period analyzing replicates of controls. All precision and accuracy values fell within the acceptable range.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467759
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Separation of human serum albumin components by RP-HPLC and CZE and their characterization by ESI-MS (1999)
    Springer
    Chromatographia 49 (1999), S. S21 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary zone electrophoresis ; Electrospray ionization-mass spectrometry ; Human serum albumin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Human serum albumin (HSA) is one of the most abundant human proteins and has been shown to be heterogeneous. A RP-HPLC method has been developed to separate HSA components in commercially available preparations. Separations were carried out on Aquapore RP-300, C8 columns using gradient elution with a combination of acetonitrile/water mobile phases containing 0.05% trifluoroacetic acid as ion-pairing agent. Optimum resolution was attained on narrow-bore columns using a stepwise, linear gradient that incorporated a shallow intermediate step of 0.20%/min in Mobile Phase B. Under similar elution conditions, separations carried out on standard-size columns showed the expected decrease in resolution due to increased peak widths. A comparative analysis of three commercial products highlighted qualitative and quantitative differences. Capillary zone electrophoresis was used for the analysis of collected RP-HPLC fractions. Results indicated that while the HPLC separation was incomplete, one of the major HPLC peaks was primarily composed of one of the three main components typically separated by CZE. ESI-MS was used to characterize the two major RP-HPLC fractions and also showed that the HPLC separation was incomplete. The MaxEnt transform of the HPLC peaks was consistent with components all being HSA and closely related derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02468972
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Megasporogenesis in Arabidopsis thaliana L.: an ultrastructural study (1999)
    Springer
    Sexual plant reproduction 12 (1999), S. 99-109 
    Details
    ISSN: 1432-2145
    Keywords: Key words Arabidopsis thaliana ; Megasporogenesis ; Meiosis ; Ultrastructure ; Cellular polarity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this study, megasporogenesis of the plant model Arabidopsis thaliana was investigated by electron microscopy for the first time. The data described here could constitute a reference for future investigations of Arabidopsis mutants. During the beginning of meiosis the megaspore mother cell shows a polarity created by unequal distribution of organelles in the cytoplasm. Plastids accumulate in the chalazal region and long parallel saccules of endoplasmic reticulum, small vacuoles and some dictyosomes are found in the micropylar region. Plasmodesmata are abundant in the chalazal cell wall. The nucleus is almost centrally localized and contains a prominent excentric nucleolus and numerous typical synaptonemal complexes. After the second division of meiosis the four megaspores are separated by thin cell walls crossed by numerous plasmodesmata and do not show significant cellular organization. The young functional megaspore is characterized by a large nucleus and a large granular nucleolus. The cytoplasm is very electron dense due to the abundance of free ribosomes and contains the following randomly distributed organelles: mitochondria, a few short saccules of endoplasmic reticulum, dictyosomes and undifferentiated plastids. However, there is no apparent polarity, except for the distribution of some small vacuoles which are more abundant in the micropylar region of the cell. The degenerating megaspores are extremely electron dense and do not show any substructure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050178
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Effects of reserpine on ECL-cell ultrastructure and histamine compartmentalization in the rat stomach (1999)
    Springer
    Cell & tissue research 295 (1999), S. 131-140 
    Details
    ISSN: 1432-0878
    Keywords: Key words ECL cells ; Gastrin ; Reserpine ; Organelles ; Ultrastructure ; Rat (Sprague-Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The histamine-storing ECL cells in the stomach play a key role in the control of acid secretion. They contain granules, secretory vesicles and microvesicles, and sustained gastrin stimulation results in the additional formation of vacuoles and lipofuscin bodies. The cells are rich in the vesicle monoamine transporter type-2 (VMAT-2), which can be inhibited by reserpine. The present study examines the effect of reserpine on ECL-cell ultrastructure and histamine compartmentalization. Rats received reserpine and/or gastrin. Reserpine was given twice by the intraperitoneal route (25 mg/kg once daily). Gastrin-17 was given by subcutaneous infusion (5 nmol/kg/h), starting at the time of the first reserpine injection and continuing for 4 days when the rats were killed. At this stage, histamine in the oxyntic mucosa was unaffected by reserpine but elevated by gastrin. Immunocytochemical analysis (confocal microscopy) showed ECL-cell histamine in control and gastrin-treated rats to be localized in cytoplasmic organelles (e.g., secretory vesicles). After treatment with reserpine alone or reserpine+gastrin, ECL-cell histamine occurred mainly in the cytosol. Planimetric analysis (electron microscopy) of ECL cells showed reserpine to increase the number, size and volume density of the granules and to reduce the size and volume density of the secretory vesicles. Gastrin reduced the number and volume density of granules and secretory vesicles, increased the number and volume density of microvesicles and caused vacuoles and lipofuscin bodies to appear. Reserpine+gastrin increased the number, volume density and size of the granules. Reserpine prevented the effects of gastrin on secretory vesicles, vacuoles and microvesicles, but did not prevent the development of lipofuscin. Our findings are in line with the views: (1) that preformed cytosolic histamine is taken up by granules/secretory vesicles via VMAT-2, that histamine is instrumental in the transformation of granules into secretory vesicles and in their consequent enlargement and (2) that vacuoles are formed by the fusion of large secretory vesicles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051219
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 19
    Electronic Resource
    Electronic Resource
    Peripheral synapses at identifiable mechanosensory neurons in the spider Cupiennius salei : synapsin-like immunoreactivity (1999)
    Springer
    Cell & tissue research 295 (1999), S. 13-19 
    Details
    ISSN: 1432-0878
    Keywords: Key words Mechanoreceptors ; Synaptic proteins ; Histochemistry ; Ultrastructure ; Slit sensilla ; Hair sensilla ; Cupiennius salei (Chelicerata)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Indirect immunocytochemical tests were used at the light- and electron-microscopic levels to investigate peripheral chemical synapses in identified sensory neurons of two types of cuticular mechanosensors in the spider Cupiennius salei Keys.: (1) in the lyriform slit-sense organ VS-3 (comprising 7–8 cuticular slits, each innervated by 2 bipolar sensory neurons) and (2) in tactile hair sensilla (each supplied with 3 bipolar sensory cells). All these neurons are mechanosensitive. Application of a monoclonal antibody against Drosophila synapsin revealed clear punctate immunofluorescence in whole-mount preparations of both mechanoreceptor types. The size and overall distribution of immunoreactive puncta suggested that these were labeled presynaptic sites. Immunofluorescent puncta were 0.5–6.8 μm long and located 0.5–6.6 μm apart from each other. They were concentrated at the initial axon segments of the sensory neurons, while the somata and the dendritic regions showed fewer puncta. Western blot analysis with the same synapsin antibody against samples of spider sensory hypodermis and against samples from the central nervous system revealed a characteristic doublet band at 72 kDa and 75 kDa, corresponding to the apparent molecular mass of synapsin in Drosophila and in mammals. Conventional transmissionelectron-microscopic staining demonstrated that numerous chemical synapses (with at least 2 vesicle types) were present at these mechanosensory neurons and their surrounding glial sheath. The distribution of these synapses corresponded to our immunofluorescence results.Ultrastructural examination of anti-synapsin-stained neurons confirmed that reaction product was associated with synaptic vesicles. We assume that the peripheral synaptic contacts originate from efferents that could exert a complex modulatory influence on mechanosensory activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Survival of rat MCH (melanin-concentrating hormone) neurons in hypothalamus slice culture: histological, pharmacological and molecular studies (1999)
    Springer
    Cell & tissue research 297 (1999), S. 23-33 
    Details
    ISSN: 1432-0878
    Keywords: Key words Melanin-concentrating hormone neurons ; Lateral hypothalamic slice culture ; Immunocytochemistry ; Ultrastructure ; In situ hybridization ; Competitive RT-PCR ; Leptin assay ; Rat (Sprague Dawley)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Hypothalamic slices containing the lateral hypothalamic area (LHA) were prepared from 6- to 8-day-old rats and maintained in stationary culture for up to 35 days in order to analyse how well the melanin-concentrating hormone (MCH) neurons survived. As previously reported for other brain areas, this method yielded a long-term well-preserved organotypic organization. Light- and electron-microscopic investigations showed that differentiation continued and that synaptic contacts developed in vitro. After a period of elimination of damaged cells and fibres, most of the remaining neurons and glial cells retained a normal morphology throughout the culture period. MCH neurons, in particular, survived well as attested by the strong immunocytochemical and in situ hybridization signals still observed after several weeks. In a comparison with the day of explantation, competitive reverse transcription/polymerase chain reaction demonstrated the remarkable stability of the level of MCH mRNA at least until the 20th day in culture; after 30 days, the clear decrease in this level seemed to be correlated with a loss of MCH neurons, rather than with a decrease in MCH expression. After 10 days of culture, the incubation of slices in the presence of the hormone leptin (50 ng/ml) resulted in a strong decrease of MCH gene expression, suggesting that MCH neurons retained their physiological properties. Thus, the LHA slice stationary culture, especially between one and three weeks (i.e. after tissue stabilization and before extensive cell loss), appears to be a suitable method for physiological and pharmacological studies of these neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051330
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 21
    Electronic Resource
    Electronic Resource
    Ultrastructure and distribution dynamics of chloride cells in tilapia larvae in fresh water and sea water (1999)
    Springer
    Cell & tissue research 297 (1999), S. 119-130 
    Details
    ISSN: 1432-0878
    Keywords: Key words Chloride cells (mitochondria-rich cells) ; Teleost larvae ; Osmoregulation ; Immunohistochemistry ; Quantification ; Ultrastructure ; Oreochromis mossambicus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Integumental and branchial chloride cells of tilapia larvae (Oreochromis mossambicus) were studied at the light-microscopical and ultrastructural level. Total numbers and distribution of chloride cells were quantified after immunostaining of cross sections of the entire larvae with an antibody against the α-subunit of Na+/K+-ATPase. The majority (66%) of Na+/K+-ATPase-immunoreactive (ir) cells, i.e. chloride cells, of freshwater tilapia larvae were located extrabranchially up to 48 h after hatching. Five days after hatching, the majority (80%) of chloride cells were found in the buccal cavity. Transfer of 24-h-old larvae to 20% sea water speeded up this process; 24 h after transfer (i.e. 48 h after hatching), the majority (59%) of chloride cells were located in the buccal cavity. The branchial chloride cell population of 24-h- and 120-h-old larvae consisted of immature, mature, apoptotic and necrotic chloride cells. However, relatively more immature chloride cells were observed in freshwater larvae (42–63%) than in (previously studied) freshwater adults (21%), illustrating the developmental state of the gills. After transfer to sea water, the incidence of degenerative chloride cells did not change. Furthermore, the incidence of immature cells had decreased and a new subtype of chloride cells, the ”mitochondria-poor” cells, appeared more frequently. These mitochondria-poor chloride cells were characterised by an abundant tubular system and relatively few mitochondria, which were aligned at the border or concentrated in one part of the cytoplasm. Most of these cells did not contact the water. The function of their enhanced appearance after seawater transfer is unknown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051339
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 22
    Electronic Resource
    Electronic Resource
    p-Hydroxymercuribenzoate as thiol-protein modifier for simultaneous determination of glycolytic enzymes by hydrophobic-interaction chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 47-53 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glycolytic enzymes ; p-Hydroxymercuribenzoate ; 203Hg-labelledp-hydroxymercuribenzoate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of hydrophobic-interaction chromatography (HIC) is proposed for the simultaneous determination of more than one thiol-protein after formation of the corresponding mercury mercaptides withp-hydroxymercuribenzoate (PHMB). The new chromatographic procedure, based on the HIC separation of the modified proteins from each other and from excess organomercury reagent has been successfully applied to the quantitative determination of phosphoglucose isomerase (PGI) and phosphoglucose mutase (PGM) in crude PGI powder, and of L-lactate dehydrogenase, PGM and aldolase in crude pyruvate kinase from rabbit muscle. The suitability of203Hg-labelled PHMB has been tested in the analysis of mixtures, which give barely distinguishable UV-peaks owing to the presence of other non-thiol components in the sample. For this purpose glyceraldehyde 3-phosphate dehydrogenase (GAPDHy) and PGIy from bakers yeast have been considered. Results obtained in experiments performed by both procedures are reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467186
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 23
    Electronic Resource
    Electronic Resource
    Determination of ethinylestradiol and gestodene in oral contraceptives by micellar electrokinetic chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 65-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar electrokinetic chromatography (MEKC) ; Oral contraceptives ; Ethinylestradiol ; Gestodene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A micellar electrokinetic chromatographic method is presented which permits quantification of ethinylestradiol and gestodene in pharmaceutical products. Separation was carried out at 25°C and 25 KV, using a 20 mM borate buffer (pH 9.2), 15 mM sodium dodecylsulfate in 30% acetonitrile-water (v/v). Under these conditions analyses were carried out in 7 min. Four different oral contraceptives were analysed and the results compared favourably with those of a reference liquid chromatographic method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467189
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 24
    Electronic Resource
    Electronic Resource
    Effect of triethylamine in the mobile phase on the retention properties of conventional polymeric and horizontally polymerized octadecylsilica in RPLC (1999)
    Springer
    Chromatographia 49 (1999), S. 635-642 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Interaction of mobile and stationary phases ; Linear solvation energy relationships ; Triethylamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of triethylamine (TEA) in the mobile phase on the RPLC retention behavior of small organic solutes has been studied on a conventional polymeric octadecylsilica (ODS) and on a horizontally polymerized ODS. Retention factors for a set of solutes were measured on the two phases with methanol-water mobile phases containing triethylamine at different concentrations and analyzed by use of linear solvation energy relationships (LSER). Variation of the resulting LSER coefficients—v (hydrophobicity),r (polarizability),s (dipolarity),b (hydrogen-bond (HB) donating acidity), anda (HB accepting strength)—were examined to see how TEA affects the intermolecular interaction properties of the mobile and stationary phases and hence the retention of the solutes. Addition of TEA to the mobile phase changes the interaction properties of both conventionally polymerized and horizontally polymerized ODS; the effect is greater for the conventional phase. The HB donating acidity (b) of conventional polymeric ODS is significantly reduced by addition of TEA. For the mobile phases studied the magnitudes of theb andv coefficients for the horizontally polymerized ODS phase are greater than for the conventional phase. The different interaction properties of the two polymeric phases arise mainly as a result of differential adsorption of TEA, because of the very different amounts of surface silanol groups present on the two phases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466905
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 25
    Electronic Resource
    Electronic Resource
    Stereoselective analysis of idrapril and its stereoisomers by reversed-phase high-performance liquid chromatography on a chiral-AGP column (1999)
    Springer
    Chromatographia 49 (1999), S. 628-634 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomer separation ; Chiral-AGP column ; Idrapril ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct liquid-chromatographic method has been developed for the stereoselective analysis of idrapril and its stereoisomers on a chiral α1 glycoprotein (AGP) column. The influence of flow-rate, temperature, and mobile phase composition on retention and selectivity was evaluated to find the optimum conditions for chiral separation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466904
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 26
    Electronic Resource
    Electronic Resource
    Separation of the enantiomers of amino and amide compounds on novel chiral stationary phases derived from a crown ether (1999)
    Springer
    Chromatographia 49 (1999), S. 621-627 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Crown ether derivatives ; Amino compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantiomers of primary amino compounds have previously been resolved on a chiral stationary phase (CSP) CSP-18C6I, prepared by immobilizing (+)-18-crown-6 tetracarboxylic acid. In this study related chiral stationary phases were prepared in an effort to broaden the scope of CSP18C6I. CSP-18C6II, synthesized to investigate the effect of spacer length, resolved the enantiomers of 2-amino-1,2-diphenylethanol and 1-(1-naphthyl)ethylamine (1-NEA) (hydrophobic amino compounds) with the largerk values and smaller α values than on CSP-18C6I, probably because of the greater hydrophobicity of CSP-18C6II. Use of CSP-18C6III, synthesized by modification of carboxylic acid functionality of CSP-18C6II by introduction of another chiral moiety,S-1-NEA, resulted in larger α values for 2-amino-1-phenylethanol and 2-amino-1-phenylpropanol than on CSP-18C6II, but the enantiomers of 1-NEA were not resolved, because of steric hindrance between 1-NEA and the chiral moiety. The amide derivativeN-3,5-dinitrobenzoyl-1-(α-naphthyl)ethylamine (DNN) as π-acceptor (3,5-dinitrobenzoyl function) or π-donor (naphthylethylamide function), and no primary amino functionality, was resolved on CSP-18C6III. The mechanism of separation of the enantiomers of DNN was assumed to be the π−π interaction between the 3,5-dinitrobenzoyl function (π-acceptor) of DNN and theS-1-NEA moiety (π-donor) of CSP-18C6III.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466903
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 27
    Electronic Resource
    Electronic Resource
    Preparation and evaluation ofp-tert-butyl-calix[4]arene-bonded silica stationary phases for high performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 643-648 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; p-tert-Butyl-calix[4]arene-bonded silica ; Nuclear magnetic resonance spectrometry ; PAHs ; Nucleosides bases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method is proposed for preparation of ap-tert-butyl-calix[4]arene-bonded silica stationary phase. The chemically modifiedp-tert-butyl-calix[4]arene is attached to silica gel via the silane coupling reagent γ-(ethylenediamino)-propyl-triethoxyl-silane. The bonded phase has been characterized by29Si and13C cross polarization/magic angle spinning solid-state nuclear magnetic spectrometry. The retention behavior of polycyclic aromatic hydrocarbons (PAHs), nucleosides and bases has been investigated on the bonded phase in the reversed-phase mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466906
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 28
    Electronic Resource
    Electronic Resource
    Preparation of branched-polyfluoroalkylsilane-coated silica gel columns and their HPLC separation characteristics (1999)
    Springer
    Chromatographia 49 (1999), S. 649-656 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyfluoroalkyl-coated silica ; 29Si CP/MAS NMR ; Polyaromatic compounds ; Fluorinated compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The conditions for reaction of the branched polyfluoroalkylsilane D3CL with silica gel have been examined. From elemental analyses and29Si NMR spectra it was found that the surface coverage and endcapping of D3CL-coated silica gel (Fluofix®) were the same as for ODS packings. The separation behavior of these phases was compared that of a variety of other packings. For polyaromatic compounds and benzene derivatives Fluofix worked in the reversed-phase mode and its retention characteristics were similar to those of C1 or CN packings. For fluorinated compound the retention characteristics of the phases is similar to those of ODS although with MeOH-water and MeCN-water mobile phases the pressure loss was lower for the fluorinated phases than for ODS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466907
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 29
    Electronic Resource
    Electronic Resource
    Peculiarities of the mechanism of retention of imidazole derivatives when using hydroxypropyl-β-cyclodextrin as mobile phase additive (1999)
    Springer
    Chromatographia 49 (1999), S. 691-698 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydroxypropyl-β-cyclodextrin ; Imidazole derivatives ; Retention mechanisms ; Enthalpy-entropy compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two different methods have been used to investigate the retention mechanism of a series of imidazole derivatives in reversed-phase liquid chromatography (RPLC) over a range of column temperatures and with different concentrations of hydroxypropyl-β-cyclodextrin (HP-β-CD) in the mobile phase. The first approach was the separate study of each factor affecting the retention mechanism; the second method was the simultaneous variation of all these factors. Changes in Van't Hoff plots as a function of HP-β-CD concentration were examined. Enthalpy and entropy were determined for two physicochemical processes: (i) solute transfer from the mobile phase to the stationary phase, and (ii) solute complexation by HP-β-CD. These thermodynamic data showed that the mechanism of retention of the solute was dependent on the concentration of HP-β-CD in the mobile phase. For a HP-β-CD concentration,C, greater than to 4 mM, from 28°C to a critical temperature,T *, solute retention was entropy-dominated because of inclusion of the solute in the HP-β-CD cavity. AboveT * retention was enthalpy-dominated, because of interaction of the solute with the RP18 stationary phase. At firstT * increased asC was increased up to a critical value,C **; it the remained relatively constant because of auto-association of the HP-β-CD molecules in the mobile phase. Enthalpy-entropy compensation revealed that HP-β-CD-solute complexation had a greater effect on retention than RP18 stationary phase-solute interaction. This confirms that the main parameter determining retention in RPLC is the distribution of the solute in the mobile phase, and that interactions with the stationary phase play a minor role.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466914
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 30
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic method for separation and quantification of intact glucosinolates (1999)
    Springer
    Chromatographia 49 (1999), S. 281-284 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucosinolates ; Rapseed-mustard ; Brassica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, economical and efficient HPLC method has been developed for the separation and determination of the individual glucosinolates in rapessed and mustard. The method involves single-step extraction of glucosinolates with boiling water and separation of the individual glucosinolates on a Novapack RP-18 column (3.9 mm ×150mm) with 0.2 M ammonium sulphate as mobile phase. Peaks were monitored at 229 nm. All major glucosinolates could be eluted within 10 min. The method proved effective for routine analysis of glucosinolates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467557
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 31
    Electronic Resource
    Electronic Resource
    Unexpected behavior of digoxin at elevated temperatures in reversed-phase liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 306-308 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Digoxin and digoxigenin ; Temperature effects ; Pore size effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Increased retention of digoxin has been observed at elevated temperatures on both 10 nm and 30 nm porediamter, RP-18 packing. This result is the opposite effect compared with the decreased retention under the same conditions with digoxin aglycon-digoxigenin. Rotation around the C−C σ-bonds in the digoxin molecule is presumed; the rod-like molecules of the newlyobtained digoxin penetrate stationary phase pores more easily thus increasing retention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467561
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 32
    Electronic Resource
    Electronic Resource
    Determination of cisplatin, transplatin and amminetri-chloroplatinate by high performance liquid chromatography in one run using 4-methyl-2-thiouracil as derivatizing agent (1999)
    Springer
    Chromatographia 49 (1999), S. 562-566 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cis-diamminedichloroplatinum (II) ; Transdiamminedichloroplatinum (II) ; Amminetri-chloroplatinate ; 4-Methyl-2-thiouracil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have developed a simple, rapid, selective and sensitive method for detecting the antitumour agent cis-diamminedichloroplatinum (II) (cisplatin) (CDDP) and its toxic impurities trans-diamminedichloroplatinum (II) (transplatin) (TDDP) amminetri-chloroplatinat (ATCP) anion using HPLC in one run. By using 4-methyl-2-thiouracil (MTU) as a derivatizing agent, new compounds have been formed from the Pt compounds and separated on a μ-Bondapak C18 column with isocratic elution and detection at 315 nm. Reactant concentration, methanol content, pH and the reaction time on yield of derivatives were investigated and the optimum conditions for the detection response were defined. The derivatives of each of the three platinum compounds formed in an acetate buffer solution containing 40% (v/v) methanol and 0.9% KCl solution at pH 3.7 and ambient temperature were only stable for one hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467760
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 33
    Electronic Resource
    Electronic Resource
    HPLC resolution of the enantiomers of glycidyl sulfides and glycidyl selenides on amylose tris-(phenylcarbamate) stationary phase (1999)
    Springer
    Chromatographia 49 (1999), S. 572-574 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantioseparations ; Amylose phenylcarbamate phase ; Glycidyl sulfides ; Glycidyl selenides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of the enantiomers of a series of glycidyl sulfides and glycidyl selenides has been examined on a chiral stationary phase prepared by coating aminopropylated silica gel with amylose tris-(phenylcarbamate). Most of the enantiomers of glycidyl monosulfides and monoselenides could be resolved satisfactorily but those of the disulfides could not. The effects of solute structure and of the concentration of 2-propanol in the mobile phase on retention and resolution were investigated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467762
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 34
    Electronic Resource
    Electronic Resource
    Structure and function of the human oocyte-cumulus-corona cell complex before and after ovulation (1999)
    Springer
    Protoplasma 206 (1999), S. 270-277 
    Details
    ISSN: 1615-6102
    Keywords: Cumulus oophorus ; Ovarian follicle ; Fertilization ; Ultrastructure ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fine structure of the human cumulus oophorus has been reviewed on the basis of scanning and transmission electron microscopic observations as well as of immunofluorescence data. Tissues sampled from preovulatory ovarian follicles and cumulus-enclosed oocytes and fertilized eggs (collected from the oviduct or obtained during in vitro fertilization procedures) have been evaluated from a microtopographic and morphodynamic point of view in order to better clarify the possible role of this population of cells. In particular, the following aspects have been studied and discussed: the presence of multiple close contacts (modulated by the interposition of the zona pellucida) between the oocyte surface and the long microvillous evaginations projecting from the inner aspect of corona cells surface (through these structures the intraovarian cumulus oophorus may control oocyte growth and metabolism up until the time of ovulation); the occurrence of different subpopulations of cells (steroid-synthetic cells, cells producing adhesive proteins, leukocytes, macrophages) in the postovulatory, extraovarian cumulus oophorus surrounding oocytes, zygotes and early developing embryos. All these elements found in the cumulus mass may positively act, through their paracrine activities, on the chemical composition of the microenvironment in which fertilization occurs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288215
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 35
    Electronic Resource
    Electronic Resource
    Trace analysis of surfactants derived from fatty alcohols II. Hydrolysis and enrichment techniques (1999)
    Springer
    Chromatographia 49 (1999), S. 12-16 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fatty alcohol sulfates ; Alkyl polyglycosides ; Trace analysis ; Steam distillation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Acid catalyzed hydrolysis of fatty alcohol sulfates under reflux condition or by microwave heating is compared. Microwave hydrolysis turned out to be faster and more convenient to use. The combination of reflux hydrolysis of fatty alcohol sulfates or alkyl polyglycosides and the simultaneous steam distillation of the generated fatty alcohols gives a very powerful sample preparation and enrichment method for fatty alcohol sulfates and alkyl polyglycosides. The preconcentrated fatty alcohols are derivatized and detected via fluorescence detection. The applicability of the method is demonstrated by the analysis of fatty alcohol sulfates in cosmetics and in river water as matrices spiked with approximately 4 ppb fatty alcohol sulfates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467180
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 36
    Electronic Resource
    Electronic Resource
    Identification and quantitation of polyphenols in leaves ofMyrtus communis L. (1999)
    Springer
    Chromatographia 49 (1999), S. 17-20 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; DAD and MS detection ; Liquid-solid extraction ; Catechin derivatives ; Myricetin derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid-solid extraction and purification procedure (LSE) was developed to identify and quantify polyphenols in the leaf tissue ofMyrtus communis L. Identification and quantitation of individual compounds was performed using HPTLC, HPLC-DAD and HPLC-MS analysis. Leaves ofMyrtus communis L. contain small amounts of phenolic acids (caffeic, ellagic and gallic acids) and quercetin derivatives (quercetin 3-O-galactoside and quercetin 3-O-rhamnoside), whereas catechin derivatives (epigallocatechin, epigallocatechin 3-O-gallate, epicatechin 3-O-gallate) and myricetin derivatives (myricetin 3-O-galactoside, myricetin 3-O-rhamnoside) are present in large amounts. This is the first report on the occurrence of galloyl-derivatives of catechin and gallo-catechin inMyrtus communis L. leaves.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467181
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 37
    Electronic Resource
    Electronic Resource
    Liquid chromatography of jasmonic acid amine conjugates (1999)
    Springer
    Chromatographia 49 (1999), S. 42-46 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral resolution ; Jasmonic acid ; Plant growth regulators ; Amine conjugates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Racemic jasmonic acid (3R,7R/3S,7S)-(±)-JA) was chemically conjugated with different biogenic amines originating from aliphatic and aromatic α-amino acids by decarboxylation. The resulting isomeric compounds were subjected to reversed-phase high-performance liquid chromatography (HPLC) and to HPLC on the chiral stationary phases Chiralpak AS and Nucleodex β-PM. Under reversed-phase conditions, all the homologous amine derivatives tested could be separated from each other except the JA-conjugates containing 2-phenyl-ethylamine and 3-methylbutylamine. On both chiral supports the (3R,7R)-(−)-JA conjugates eluted earlier than those of the enantiomeric counterpart (3S,7S)-(+)-JA. On Chiralpak AS all the isomers studied could be separated to baseline with a mobile phase containingn-hexane and 2-propanol. The calculated resolution factors were between 1.80 and 4.17. The pairs of isomers were also chromatographed on the cyclodextrin stationary phase Nucleodex β-PM with methanol-triethylammonium acetate buffer as mobile phase. Under these conditions resolution factors were between 0.74 and 1.29. The individual isomers were chiroptically characterized by measurement of their circular dichroism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467185
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 38
    Electronic Resource
    Electronic Resource
    Separation of the enantiomers of amino acid esters as benzophenone imine derivatives on polysaccharide-derived chiral stationary phases (1999)
    Springer
    Chromatographia 49 (1999), S. 61-64 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Benzophenone imine derivatives ; Amino acid esters ; Enantiomer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid-chromatographic separation of the enantiomers of amino acid esters as benzophenone Schiff-base derivatives on polysaccharide-derived chiral stationary phases (CSPs) is described. The performance of Chiralcel OF was superior to that of the other CSPs for resolution of benzophenone imine derivatives of amino acid ethyl and methyl esters. The enantiomers of most of the amino acid esters examined as their benzophenone imine derivatives were resolved to baseline on Chiralcel OF. The L-(−) enantiomers of all the analytes were preferentially retained on Chiralcel OF. The resolution of several imine derivatives of amino acid esters was investigated, as was the effect of eluent composition on the resolution of amino acid ethyl esters as their benzophenone imine derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467188
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 39
    Electronic Resource
    Electronic Resource
    Development and validation of an HPLC method for the simultaneous determination of clozapine and desmethylclozapine in plasma of schizophrenic patients (1999)
    Springer
    Chromatographia 49 (1999), S. 75-80 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amperometric detection ; Clozapine ; Desmethylclozapine ; Drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method with amperometric detection has been developed for the determination of levels of clozapine (CLZ) and its active metabolite N-desmethylclozapine (DMC) in human plasma. The analysis was performed on a 5 μm C8 reversed phase column (150×4.6 mm i.d.), with acetonitrile-phosphate buffer (pH 3.5), as the mobile phase. The detection voltage was +800 mV and the cell and column temperature were 50°C. Linear responses were obtained between 2 ng mL−1 and 100 ng mL−1. Absolute recovery for both clozapine and desmethylclozapine exceeded 88% and the detection limit was 1 ng mL−1. Repeatability, intermediate precision and accuracy were satisfactory. The method, which is rapid, sensitive and selective, has been applied to therapeutic drug monitoring in schizophrenic patients following administration of Leponex® tablets. In 21 patients in steady state at a mean daily clozapine dosage of 358 mg (ranging from 150 to 500 mg day−1), clozapine levels averaged 379 ng mL−1 (ranging from 102 to 818 ng mL−1) and DMC levels averaged 233 ng mL−1 (ranging from 70 to 540 ng mL−1). The method requires only a very small amount of plasma (100 μL), and thus it is suitable for pharmacokinetic studies, as well as for therapeutic drug monitoring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467191
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 40
    Electronic Resource
    Electronic Resource
    Determination of yttrium and lanthanum in zirconium dioxide by HPLC, X-ray fluorescence and neutron activation analyses (1999)
    Springer
    Chromatographia 49 (1999), S. 91-94 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Zirconium oxide ceramics ; X-ray fluorescence ; Neutron activation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lanthania-and yttria-stabilized zirconium oxide ceramics have been examined using High Performance Liquid Chromatography (HPLC), thermal neutron activation (NA) and X-ray Fluorescence (XRF) analyses and thus determine the stabilizer content. Ceramic powders with the composition ZrO2:x mol % La2O3 (x=5, 10, 15, 20 and 33) and ZrO2:x mol % Y2O3 (x=10, 15, 20 and 25) were prepared by the citrate and the co-precipitation techniques, respectively. The lanthanum content was determined by HPLC (x=5.09, 9.78, 14.98, 19.81 and 25.94) and NA (x=5.15, 10.32, 17.25, 21.08 and 27.97) analyses, the yttrium content by HPLC (x=8.5, 13.5, 17.9 and 22.1) and XRF (x=9.9, 15.8, 20.1 and 24.9) analyses. An experimental sequence, based on continuous dilution of ceramic powder solutions, is proposed for preparing samples for HPLC measurements. A swimming pool nuclear reactor is used for NA analysis. The quantitative determinations of yttrium and lanthanum doping levels obtained using those techniques are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467194
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 41
    Electronic Resource
    Electronic Resource
    Study of the chromatographic behavior and inclusion constants of new fluorescence agents by use of cyclodextrin additives under conditions of steady- and dynamic-state equilibrium and with fluorescence detection (1999)
    Springer
    Chromatographia 49 (1999), S. 95-104 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrin additives ; Fluorescence agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We report four new derivatization agents, acridone-N-acetic acid (ARC), carbazole-9-ylacetic acid (CRA), carbazole-9-ylpropionic acid (CRP), and 2-methyl-2-carbazole-9-ylacetic acid (MCRA), with strong fluorescence emission which has low dependence on solvent polarity. The emission maxima for ARC, CRA, CRP, and MCRA were 430 nm (λex 404 nm), 368 nm (λex 335 nm), 356 nm (λex 340 nm) and 360 nm (λex 330 nm), respectively. The effects of mobile-phase composition, pH, and temperature on the liquid chromatographic retention behavior of the four fluorescence agents were investigated. An experimental model was established for calculating the inclusion constants of cyclodextrin (CD) complexes in the dynamic state, using β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as examples, and different mobilephase compositions. On the basis of the model, the inclusion constants of the solutes in pure water (K fw) were determined by extrapolation. The thermodynamic parameters (ΔH o and ΔS o) and dissociation constantsK am for the solutes in this chromatographic system were obtained by means of capacity factor (k) values using a corresponding model formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467195
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 42
    Electronic Resource
    Electronic Resource
    Stereochemical resolution of racemates, in HPLC, using a chiral stationary phase based upon immobilized α-chymotrypsin. II. Enzyme chiral separations (1999)
    Springer
    Chromatographia 49 (1999), S. 606-614 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin-CSP ; Enzymatic chiral separations ; Loadability evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several racemates has been resolved according to an enzymatic recognition mechanism on an α-chymotrypsin chiral stationary phase. The loadability of the ACHT-CSP has been evaluated both in buffered and non-buffered mobile phases under the enzymatic process and compared with the loading capacity obtained by the structural recognition process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466901
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 43
    Electronic Resource
    Electronic Resource
    Stereochemical resolution of racemates, in HPLC, using a chiral stationary phase based upon immobilized α-chymotrypsin. I. Structural chiral separations (1999)
    Springer
    Chromatographia 49 (1999), S. 595-605 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Chymotrypsin immobilized on silica ; In situ immobilization process ; Structural chiral separations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary α-Chymotrypsin was immobilized on an epoxide derivatized silica gel by anin situ immobilization process. Several racemates were resolved by a structural recognition mechanism. The immobilization process and the stability of this α-chymotrypsin stationary phase have been studied. The mobile phase parameters including the ionic strength, pH and the effects of organic modifiers have been also investigated. The retention, efficiency and stereoselectivity of the solutes appear to be related to their molecular structure, hydrophobicity and electrostatic interactions. These relationships determine the recognition mechanism and the position of each enantiomer in the active site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466900
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 44
    Electronic Resource
    Electronic Resource
    Improved separation of polyethylene glycols widely differing in molecular weight range by reversed-phase high performance liquid chromatography and evaporative light scattering detection (1999)
    Springer
    Chromatographia 49 (1999), S. 615-620 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light-scattering detection ; MALDI-TOF ; Polyethylene glycols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polyethylene glycols (PEGs) of nominal molecular weight (M) 200, 400, 600, 1000, 1500, 3000, 4000 and 6000 were chosen as model compounds and subjected to reversed-phase high performance liquid chromatography (RP-HPLC) on an octadecasilyl silica gel (C18) stationary phase using a binary gradient composed of acetonitrile and water and evaporative light scattering detection (ELSD). Satisfactory resolution of oligomers up to M of 3000 was accomplished; the higher M samples PEG-4000 and PEG-6000 could not be further resolved into the constituent oligomers and therefore, M=4000 marks the upper limit of oligomer resolution. Despite some peak overlapping as a consequence of the more or less broad oligomer distribution, individual types of PEG samples can be distinguished from each other by their characteristic chromatographic fingerprint patterns, as shown with a mixture consisting of PEG-400, PEG-1000, PEG-3000, PEG-4000 and PEG-6000. For this reason, the method is well-suited for characterization of samples containing PEGs widely differing in M. In addition, matrix assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF/MS) performed with PEG-600, PEG-1000 and PEG-3000 revealed that the optimum degree of oligomer resolution has been achieved by use of the present method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466902
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 45
    Electronic Resource
    Electronic Resource
    Determination of alcohols using condensation agent carbazole-9-acetyl-benzene-disulfonate by high performance liquid chromatography with pre-column fluorescence derivatization (1999)
    Springer
    Chromatographia 49 (1999), S. 657-665 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alcohols ; Pre-column fluorescence derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive LC method for the determination of alcohols, using fluorescent condensation agent carbazole-9-N-acetylbenzne-disulfonate(CABS), has been developed. A mixture of alcohols and triethylamine catalyst in dichloromethane or chloroform is treated with CABS to give quantitative yields of esters. Emission maximum for the derivatized alcohols is 365 nm (λex 335 nm). The labeled derivatives are very stable, no significant decomposition is observed after heating in 40% at 40°C for 24 h. The method, in conjunction with a multigradient program, offers baseline resolution of common alcohol derivatives on a reversed-phase C18 column. Studies on derivatization conditions indicate that primary and secondary alcohols react very fast with CABS in the presence of triethylamine in dichloromethane or chloroform to give the corresponding fluorescent derivatives. This method is more convenient and more efficient than previous methods which require prior conversion of carboxylic acids to acyl chlorides. The separation of alcohol derivatives has good reproducibility and the rsd's (n=5) for 50 pmol of each alcohol are 4%. Detection limits are at the fmol level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466908
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 46
    Electronic Resource
    Electronic Resource
    Hydrolysis of microcystins and nodularin by microwave radiation (1999)
    Springer
    Chromatographia 49 (1999), S. 671-677 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microwave hydrolysis ; Microcystin ; Nodularin ; D- and L-selective amino acid determination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Microwave radiation has been successfully used for hydrolysis of the hepatotoxic cyclic peptides microcystins and nodularin. Set-up of the microwave device and the operating conditions for microwave hydrolysis were optimized. Results of the microwave hydrolysis were compared with results from conventional hydrolysis for 24 h at 110°C. Microwave hydrolysis of microcystins and nodularin for as little as 10 min at 160°C results in complete cleavage of peptide bonds and high recoveries of amino acids. Enantioselective determination of amino acids was achieved by use of a previously described HPLC method after pre-column derivatization withortho-phthaldialdehyde and the chiral thiolN-iso-butyryl-cysteine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466910
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 47
    Electronic Resource
    Electronic Resource
    Analysis of commercial ceramides by non-aqueous reversed-phase liquid chromatography with evaporative light-scattering detection (1999)
    Springer
    Chromatographia 49 (1999), S. 241-248 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-aqueous reversed-phase liquid chromatography ; Evaporative light-scattering detection ; Octadecyl grafted silica ; Ceramides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper describes the development of a chromatographic system for analysis of commercial ceramides structurally similar to those found in the stratum corneum. The ceramides used in this study contain different amine based (phytosphingosine, sphingosine and dihydrosphingosine) and fatty acids of different chain lengths and with different functional groups (hydroxylated and unsaturated). Non-aqueous reversed-phase (NARP) liquid chromatography with evaporative light-scattering detection (ELSD) were the techniques chosen in accordance with the nature of the ceramides. The eluent strength and the potential selectivity of different organic solvents were investigated. On a C18-bonded silica, the most promising chromatographic conditions employed a gradient from ACN-THF, 95∶5, to ACN-THF-PrOH, 35∶5∶60, in 15 min with a constant concentration of TEA (10 mM) and a stoichiometric amount of formic acid.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467550
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 48
    Electronic Resource
    Electronic Resource
    Normal-phase high performance liquid chromatographic separation and characterization of short- and long-chain triacylglycerols (1999)
    Springer
    Chromatographia 49 (1999), S. 363-368 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light scatering detection ; APCI mass spectrometry ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Short- and long-chain triacylglycerols (SLCT) are a family of lipids prepared by chemical or enzymatic interesterification of triacetin, tripropionin and/or tributyrin, and long-chain (C16!18) hydrogenated vegetable oils. In this study, a normal-phase cyanopropyl high-performance liquid chromatographic (HPLC) method was developed for the separation and quantification of SLCT. The method is capable of separating SLCT mixtures, free fatty acids and the neutral lipid classes of saturated long-chain triacylglycerols, diacylglycerols and monoacylglycerols. To characterize the specific SLCT classes, a normal-phase HPLC procedure using a non-modified silica column was developed to separate the SLCT into individual isomers based on total carbon number and position of fatty acids on the glycerol backbone. Online coupling with a mass detector (LC/MS) allowed the identification of the individual triacylglycerol structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467607
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 49
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic determination/identification of oxytetracycline and sulphadimidine in meat and eggs (1999)
    Springer
    Chromatographia 49 (1999), S. 369-373 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sep-Pak CN cartridge ; Oxytetracycline ; Sulphadimidine ; Meat and eggs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid method for the simultaneous determination/identification of residual oxytetracycline (OTC) and sulphadimidine (SDD) in meats (beef, pork, chicken) and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of OTC and SDD was performed using a Sep-Pak® CN cartridge. The extracts contained OTC/SDD analytes when examined by HPLC using a LiChrospher® 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photodiode array detector. The average recoveries from spiked samples (0.1 μg g−1 and 1.0 μg g−1) were in excess of 80.2% with coefficients of variation between 1.5 and 5.0%. The limits of detection for OTC and SDD were 0.05 and 0.02 μg g−1, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467608
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 50
    Electronic Resource
    Electronic Resource
    High performance liquid chromatography coupled to nuclear magnetic resonance spectroscopy and mass spectrometry applied to plant products: Identification of ecdysteroids fromSilene otites (1999)
    Springer
    Chromatographia 49 (1999), S. 374-378 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; NMR spectroscopy and mass spectrometry ; Plant products ; Silene otites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC coupled in parallel to nuclear magnetic resonance (NMR) and mass spectrometry (MS) has been used to obtain1H NMR and mass spectra of a number of ecdysteroids present in an extract of the plantSilene otites. Reversed phase gradient chromatography was performed using a D20-acetonitrile-based solvent system. NMR and mass spectra were obtained for integristerone A, 20-hydroxyecdysone, 2-deoxy-20-hydroxyecdysone and 2-deoxyecdysone to provide structural confirmation using continuous and stopped flow HPLC-NMR. The combined HPLC-NMR-MS system described here provided a more comprehensive analysis of the ecdysteroids present in the extract than HPLC-NMR alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467609
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 51
    Electronic Resource
    Electronic Resource
    Comparison of octadecyl bonded titania phases (1999)
    Springer
    Chromatographia 49 (1999), S. 424-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Octadecyl titania ; Surface hydrosilation ; Solid-state NMR C7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The structure of a C18 phase based on titania (C18-A), synthesized by the method of solution polymerization, is investigated by diffuse reflectance infrared Fourier transform (DRIFT) and solid-state nuclear magnetic resonance (NMR) spectroscopy. The findings are compared with the results of a second C18 phase based on titania (C18-B) which was synthesized by the method of surface hydrosilation. The dynamic behavior of both phases is examined by1H MAS NMR detection of spinlattice relaxation times in the rotating frame (T1pH) and conventional spin-lattice relaxation times (T1). Due to a smaller ligand density, phase C18-A appears to be a somewhat more mobile than phase C18-B. The chromatographic capability of the phase C18-A is demonstrated by the separation of samples containing benzene derivates or anilines. The elution order is analogous to the phase C18-B, but for both test mixtures the polarity of the mobile phase has to be increased. Phase C18-A is classified as being polymeric by the Sander and Wise test, whereas phase C18-B shows intermediate retention behavior.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467618
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 52
    Electronic Resource
    Electronic Resource
    Determination of ochratoxin a in beer by high-performance liquid chromatography (1999)
    Springer
    Chromatographia 49 (1999), S. 543-546 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; MS-MS detection ; Electrospray-Ionization (ESI) ; Beer ; Ochratoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Ochratoxin A (OTA) is a nephrotoxic and nephrocacinogenic mycotoxin commonly produced by several ubiquitousAspergillus andPenicillium species. OTA is found predominantly in cereals and derived products, and therefore OTA may be transferred into beer from contaminated grain. Thirty-five samples of German beers were analyzed: OTA was extracted with toluene and purified by solid phase extraction using silica cartridges. OTA was determined by high-performance liquid chromatography with fluorescence detection. Since of fluorescence detection is not specific in this instance, the beer samples were also analyzed by high-performance liquid chromatography electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS). OTA levels in the range of 0.1–0.2 μg L−1 were found in 9 beer samples, 21 samples contained trace amounts of OTA (〈0.1 μg L−1) and in 5 samples no OTA was detectable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467756
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 53
    Electronic Resource
    Electronic Resource
    Anatomical and ultrastructural changes of the floral nectary ofPisum sativum L. during flower development (1999)
    Springer
    Protoplasma 206 (1999), S. 57-72 
    Details
    ISSN: 1615-6102
    Keywords: Anatomy ; Floral nectary ; Modified stomata ; Phloem ; Pisum sativum ; Stereology ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The floral nectary ofPisum sativum L. is situated on the receptacle at the base of the gynoecium. The gland receives phloem alone which departed the vascular bundles supplying the staminal column. Throughout the nectary, only the companion cells of the phloem exhibited wall ingrowths typical of transfer cells. Modified stomata on the nectary surface served as exits for nectar, but stomatal pores developed well before the commencement of secretion. Furthermore, stomatal pores on the nectary usually closed by occlusion, not by guard-cell movements. Pore occlusion was detected most frequently in post-secretory and secretory glands, and less commonly in pre-secretory nectaries. A quantitative stereological study revealed few changes in nectary fine structure between buds, flowers secreting nectar, and post-secretory flowers. Dissolution of abundant starch grains in plastids of subepidermal secretory cells when secretion commenced suggests that starch is a precursor of nectar carbohydrate production. Throughout nectary development, mitochondria were consistently the most plentiful organelle in both epidermal and subepidermal cells, and in addition to the relative paucity of dictyosomes, endoplasmic reticulum, and their associated vesicles, the evidence suggests that floral nectar secretion inP. sativum is an energy-requiring (eccrine) process, rather that granulocrine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279253
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 54
    Electronic Resource
    Electronic Resource
    Ultrastructural study of the relationship between generative and vegetative cells inMagnolia ×soulangeana Soul.-Bod. pollen grains (1999)
    Springer
    Protoplasma 206 (1999), S. 87-96 
    Details
    ISSN: 1615-6102
    Keywords: Plasmalemmic cord ; Pollen grain ; Ultrastructure ; Magnolia ×soulangeana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary InMagnolia ×soulangeana pollen grains the generative cell (GC) does not become totally free within the vegetative cell (VC), at least until the pollen tube emergence. Due to a deviation in its detachment process from the sporoderm, the opposing ends of the VC plasmalemma do not fuse themselves when the GC moves away from the intine. Consequently, the interplasmalemmic space surrounding the GC does not become isolated but rather maintains continuity with the sporoderm through a complex formation that we have called plasmalemmic cord. The real existence of this formation was confirmed through serial sectioning showing the plasmalemmic cord to consist of the VC plasmalemma. In its initial portion it is occupied by a reasonably accentuated wall ingrowth of the inner layer of the intine (intine 3). In the remainder portion, neither of the cytochemical tests used in this work have revealed the presence of a significant amount of wall material. However, ultrathin sections of samples processed either chemically or by cryofixation showed the existence of an intricate system of tubules and vesicles, some of which are evaginations of the VC plasmalemma. The hypothesis that the plasmalemmic cord may have a role in the complex interactions between the two pollen cells is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279255
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 55
    Electronic Resource
    Electronic Resource
    Distribution and transmission of endosymbiotic microorganisms in the oocytes of the pig louse,Haematopinus suis (L.) (Insecta: Phthiraptera) (1999)
    Springer
    Protoplasma 209 (1999), S. 207-213 
    Details
    ISSN: 1615-6102
    Keywords: Endosymbiont ; Mycetocyte ; Mycetome ; Oocyte ; Transovarial transmission ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary All anoplurans live symbiotically with prokaryotic microorganisms hosted in specialized cells, termed mycetocytes. In nymphs and males mycetocytes are distributed between midgut epithelial cells. In females, besides the midgut, mycetocytes are found in the reproductive organs where they are located at the base of ovarioles in contact with lateral oviducts. The mycetocyte-associated symbionts are transmitted from one generation to the next transovarially. Here, the results of histological and ultrastructural studies on the distribution and transmission of symbiotic microorganisms within the ovaries of the anopluranHaematopinus suis are presented. Interestingly, during advanced oogenesis (i.e., choriogenesis) of this species all symbionts are localized extracellularly and form a tight mass located at the posterior pole of the oocyte just below the hydropyle. In insects studied so far, such localization of transovarially transmitted microorganisms has been reported only in the closely related speciesHaematopinus eurysternus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01453449
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 56
    Electronic Resource
    Electronic Resource
    Effect of high-level oxygen exposure on the peroxidase activity and the neuromelanin-like pigment content of the nerve net in the earthworm, Lumbricus terrestris (1999)
    Springer
    Cell & tissue research 295 (1999), S. 349-354 
    Details
    ISSN: 1432-0878
    Keywords: Key words Neuromelanin ; Neuron ; Peroxidase ; Oxygen metabolism ; High-definition light microscopy ; Electron microscopy ; Ultrastructure ; Cytochemistry ; Substantia nigra ; Lumbricusterrestris (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Histochemical examination of 1-μm tissue sections from the dorsal nerve plexus of the earthworm, Lumbricus terrestris, reveals multiple brown intraneuronal granules. These granules contain material morphologically and histochemically consistent with neuromelanin. When viewed with transmission electron microscopy, these were seen as single membrane-enclosed biphasic granules with diameters of 370–730 nm. Exposure of L. terrestris to high-level environmental oxygen resulted in an increase in the number of neuromelanin-like pigment granules within the neurons of the circular muscle layer. As measured by ortho-phenylenediamine hydrochloride, the endogenous peroxidase activity of extracts from worms incubated in high-level environmental oxygen was 51% more than controls. The endogenous peroxidase activity was localized in situ with 3,3-diaminobenzidine (DAB) and was found to increase in and around the neuromelanin-like pigment-containing neurons within the circular muscle layer. These studies suggest that the nerve net of L. terrestris may serve as a model to study the role of neuromelanin production in oxidative stress and its relationship to endogenous peroxidases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051241
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 57
    Electronic Resource
    Electronic Resource
    The distribution and ultrastructure of class II MHC-positive cells in human dental pulp (1999)
    Springer
    Cell & tissue research 295 (1999), S. 151-158 
    Details
    ISSN: 1432-0878
    Keywords: Key words Class II MHC-positive cells ; Human leukocyte antigen-DR ; Dental pulp ; Dendritic cells ; Macrophages ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The distribution and ultrastructure of class II major histocompatibility complex (MHC)-positive cells were investigated in human dental pulp, employing immunohistochemistry using an anti-human leukocyte antigen (HLA)-DR-monoclonal antibody. HLA-DR-immunopositive cells, appearing spindle-like or dendritic in profile, were densely distributed throughout the dental pulp. Under the electron microscope, these cells exhibited various sizes of vesicles containing clear or opaque contents, multivesicular bodies and characteristic fine tubulovesicular structures in their cytoplasm. Some reactive cells possessed coated pits and vesicles including electron-dense materials, indicating an active endocytosis. At the periphery of the pulp tissue, the HLA-DR-immunopositive cells were predominantly situated in the subodontoblastic layer, with some located in the odontoblast layer and/or predentin and extending their cytoplasmic processes into the dentinal tubules. Cell processes of these cells occasionally made contact with several odontoblast processes in the same way as the nerve fibers in the predentin. These cells never contained the typical phagosomes frequently observed in the HLA-DR-immunoreactive macrophages in the subodontoblastic layer and the pulp core. The results suggest that the HLA-DR-immunopositive cells in the odontoblast layer and/or predentin have some regulatory function on the odontoblasts under physiological conditions, in addition to their involvement in the initial defense reaction after tooth injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051221
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 58
    Electronic Resource
    Electronic Resource
    Androgen-induced changes in Leydig cell ultrastructure and steroidogenesis in juvenile African catfish, Clarias gariepinus (1999)
    Springer
    Cell & tissue research 297 (1999), S. 291-299 
    Details
    ISSN: 1432-0878
    Keywords: Key words Teleost fish ; Puberty ; Testes ; Sex steroids ; Ultrastructure ; Steroidogenesis ; Clarias gariepinus (Teleostei)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The present report focuses on the mechanism(s) involved in the steroid-induced decrease of androgen production in immature African catfish testes that was observed in previous studies. Juvenile animals were implanted with Silastic pellets containing different 11-oxygenated androgens (11-ketotestosterone, KT; 11β- hydroxyandrostenedione, OHA; 11-ketoandrostenedione, KA), testosterone (T) or estradiol-17β (E2). Control groups received steroid-free pellets. Two weeks later, testis tissue fragments were either incubated with increasing concentrations of catfish luteinizing hormone (LH), or incubated with [3H]-pregnenolone ([3H]-P5) or [3H]-androstenedione ([3H]-A). Tissue fragments were also prepared for the quantitative assessment of Leydig cell morphology. Most of the parameters studied were not affected significantly by implantation of E2. Implantation of all androgens inhibited both the basal and the LH-stimulated androgen secretory capacity in vitro. This was associated with a reduced size of the Leydig cells and loss of half of their mitochondria. The studies on the metabolism of tritiated steroid hormones indicated that steroidogenic steps prior to 11β-hydroxylation, probably C17–20 lyase activity, were affected by all androgens. Although the effects of 11-oxygenated androgens and T on Leydig cells were mostly similar, previous work showed that only the 11-oxygenated androgens stimulated spermatogenesis, suggesting that distinct mechanisms of action are used by 11-oxygenated androgens and T. These mechanisms, however, seem to merge on the same target(s) to impair Leydig cell androgen production. Such a negative feedback mechanism may be of relevance in the context of the decline in androgen secretion per milligram testis tissue that accompanies the first wave of spermatogenesis in pubertal African catfish.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051357
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 59
    Electronic Resource
    Electronic Resource
    Echinococcus granulosus: praziquantel treatment against the metacestode stage (1999)
    Springer
    Parasitology research 85 (1999), S. 999-1006 
    Details
    ISSN: 1432-1955
    Keywords: Key wordsEchinococcus granulosus ; Praziquantel ; Metacestode ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The efficacy of praziquantel against the metacestode of Echinococcus granulosus was studied by means of in vitro incubations or in vivo experiments. The results of in vitro incubations indicated that the effectiveness of praziquantel was higher when the parasite material comprised cysts from cyst masses than in the case of intact cysts that retained their adventitial layer. Ultrastructural alterations in the germinal layer of collapsed cysts incubated in vitro were detected. The results obtained in mice after 4 months of treatment demonstrated no significant difference between the control and treated groups with regard to the number and wet weight of developed cysts. However, ultrastructural alterations were detected in the cyst tissue that were similar to those described in the in vitro experiment. In contrast, the effect of chemoprophylaxis on the number and the wet weight of developed cysts was extremely significant as compared with the control value, the efficacy being 99.41% and 98.32%, respectively. Moreover, ultrastructural observations of the cyst tissue revealed loss of its integrity, and no intact cyton was observed in the germinal layer of the developed cyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004360050672
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 60
    Electronic Resource
    Electronic Resource
    Morphology and ultrastructure of the anterior adhesive areas of the capsalid monogenean parasites Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanus carponotatus (Pisces: Lutjanidae) (1999)
    Springer
    Parasitology research 85 (1999), S. 399-408 
    Details
    ISSN: 1432-1955
    Keywords: Key words Monogenea ; Capsalidae ; Benedenia rohdei ; B. lutjani ; Ectoparasites ; Lutjanus carponotatus ; Glands ; Ultrastructure ; Adhesion ; Attachment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The anterior adhesive areas of Benedenia rohdei from the gills and B. lutjani from the pelvic fins of Lutjanuscarponotatus at Heron Island, Australia, were studied using scanning and transmission electron microscopy. All specimens were fixed when detached from host tissue. Both monogenean species have two disc-like anteroventral attachment organs, each of which has an anterolateral adhesive area divided into three adjacent zones by tegument from the ventral surface of the attachment organ. A rod-shaped secretion and a smaller, roughly spherical secretion are associated with the anterior adhesive areas in both species; a third type of secretion occurs anteriorly but outside these adhesive areas. The electron-dense spherical secretory bodies released onto the anterior adhesive zones in these Benedenia spp. are of a single type and differ ultrastructurally from those previously reported in monogeneans living on teleost hosts. A correlation, therefore, between secretion morphology and host type is not supported. No relationship was found between parasite microhabitat and secretion morphology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004360050566
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 61
    Electronic Resource
    Electronic Resource
    Electrophysiological and ultrastructural correlates of cryoinjury in sciatic nerve of the freeze-tolerant wood frog, Rana sylvatica (1999)
    Springer
    Journal of comparative physiology 169 (1999), S. 351-359 
    Details
    ISSN: 1432-136X
    Keywords: Key words Freeze tolerance ; Sciatic nerve ; Cryoinjury ; Dehydration ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated function and ultrastructure of sciatic nerves isolated from wood frogs (Rana sylvatica) endemic to the Northwest Territories, Canada, following freezing at −2.5 °C, −5.0 °C, or −7.5 °C. All frogs frozen at −2.5 °C, and most frogs (71%) frozen at −5.0 °C, recovered within 14 h after thawing began; however, frogs did not survive exposure to −7.5 °C. Sciatic nerves isolated from frogs frozen at −7.5 °C were refractory to electrical stimulation, whereas those obtained from frogs surviving exposure to −2.5 °C or −5.0 °C generally exhibited normal characteristics of compound action potentials. Frogs responded to freezing by mobilizing hepatic glycogen reserves to synthesize the cryoprotectant glucose, which increased 20-fold in the liver and 40-fold in the blood. Ultrastructural analyses of nerves harvested from frogs in each treatment group revealed that freezing at −2.5 °C or −5.0 °C had little or no effect on tissue and cellular organization, but that (lethal) exposure to −7.5 °C resulted in marked shrinkage of the axon, degeneration of mitochondria within the axoplasm, and extensive delamination of myelin sheaths of the surrounding Schwann cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003600050231
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 62
    Electronic Resource
    Electronic Resource
    Articular chondrocytes and synoviocytes in a co-culture system: influence on reactive oxygen species-induced cytotoxicity and lipid peroxidation (1999)
    Springer
    Cell & tissue research 296 (1999), S. 555-563 
    Details
    ISSN: 1432-0878
    Keywords: Key words Chondrocyte ; Synoviocyte ; Co-culture ; Proliferation ; Lipid peroxidation ; Cytotoxicity ; Ultrastructure ; Rat (Wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Objective: A new co-culture system of rat articular chondrocytes and synoviocytes (HIG-82; cell line) was incubated with phorbol myristate acetate (PMA), H2O2 or a combination of Fe2+ and ascorbic acid to simulate inflammation-like radical attacks in articular joints. Methods: Chondrocytes were characterized by immunocytochemistry against collagen type II, transmission electron (TEM) and light microscopy. Lipid peroxidation was investigated by measuring thiobarbituric-acid-reactive material in the supernatants, cytotoxicity by determining release of lactate dehydrogenase and proliferation by measuring [3H]thymidine incorporation, culture protein and DNA. Results: PMA or Fe2+ and ascorbic acid induced lipid peroxidation in chondrocytes and synoviocytes that was decreased significantly in co-cultures. PMA and H2O2 dose dependently induced release of lactate dehydrogenase in chondrocytes, which was lowered in co-cultures or in previously co-cultured chondrocytes to a nearly basal level. In contrast, conditioned media of synoviocyte cultures showed no lowering effect on the radical-induced toxicity. Protection against H2O2-induced damage of cellular membranes by co-culturing was also shown by TEM. Synoviocytes released chondrocyte-stimulating growth factors spontaneously without previous interaction. Conclusion: Chondrocytes establish protective mechanisms against reactive oxygen species via an interaction with synoviocytes. Our co-culture model presents a possible way to study mechanisms of inflammation in articular joints under defined conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051317
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 63
    Electronic Resource
    Electronic Resource
    Phylogenetic affiliation and ultrastructure of uncultured magnetic bacteria with unusually large magnetosomes (1998)
    Springer
    Archives of microbiology 169 (1998), S. 136-147 
    Details
    ISSN: 1432-072X
    Keywords: Key words Magnetic bacteria ; Biomineralization ; Magnetite ; 16S rRNA ; In situ hybridization ; Ultrastructure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Natural enrichments of magnetic bacteria from the Itaipu lagoon near Rio de Janeiro were dominated by coccoid-to-ovoid morphotypes that produced unusually large magnetosomes. To determine the phylogenetic position of these unusual microorganisms, 16S rRNA genes were retrieved from bacteria magnetically separated from sediment of the Itaipu lagoon by in vitro amplification and cloning of PCR products into a plasmid vector. Partial sequencing of the obtained clones revealed two clusters of closely related sequences affiliated to a distinct lineage consisting exclusively of magnetic bacteria within the α-subclass of Proteobacteria. For a detailed phylogenetic analysis, several almost complete sequences of the 16S rRNA genes were determined. One representative clone of each cluster provided a PCR template for the in vitro transcription of group-specific polynucleotide probes complementary to a variable region of the 16S rRNA molecule. At least three different morphotypes of magnetic bacteria were reliably identified by post-embedding hybridization of ultra-thin sections. Electron microscopic analyses of hybridized cells enabled for the first time a detailed description of the morphological variety and ultrastructure of phylogenetically identified, uncultured magnetic bacteria. Two distinct coccoid bacteria were identified by the transcript probe complementary to the 16S rRNA sequence mabrj12, whereas the probe complementary to the sequence mabrj58 allowed the identification of an ovoid morphotype that displayed magnetosomes with the largest volumes observed to date.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050553
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 64
    Electronic Resource
    Electronic Resource
    The chromatographic behavior of arsenic compounds on anion exchange columns with binary organic acids as mobile phases (1998)
    Springer
    Chromatographia 47 (1998), S. 257-263 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange chromatography ; Anion-exchange chromatography ; Arsenic compounds ; Flame atomic absorption detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Identification and quantification of arsenic compunds was performed with high- performance liquid chromatography (HPLC) and flame atomic absorption spectrometry (FAAS) as element-specific detector. Arsenous acid, methylarsonic acid, dimethylarsinic acid, arsenic acid, arsenobetaine, and arsenocholine were separated on two anion-exchange columns (Synchropak Q 300 and PRP-X 100) with different binary organic acids as mobile phases. The infleunce of chromatographic parameters, such as pH and the concentration of the mobile phase were investigated. An unusual chromatographic behavior of arsenous acid was observed when tartaric acid was used as mobile phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466529
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 65
    Electronic Resource
    Electronic Resource
    The application of high performance liquid chromatography, coupled to nuclear magnetic resonance spectroscopy and mass spectrometry (HPLC-NMR-MS), to the characterisation of ibuprofen metabolites from human urine (1998)
    Springer
    Chromatographia 47 (1998), S. 264-270 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; NMR and MS detection ; Ibuprofen metabolites ; Urine extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of HPLC-NMR-MS for the detection and identification of the metabolites of ibuprofen present in a solid phase extract of human urine is described. Gradient reversed-phase HPLC was used to separate the components present in the extract, which were then characterised by a combination of stopped-flow1H NMR and on line electrospray-MS. This approach led to the rapid identification of the known phase 1 human metabolites of ibuprofen, including hydroxy- and carboxy- metabolites, together with their respective glucuronide conjugates. In addition a probable artefact resulting from the dehydration of one of the side chainhydroxylated glucuronides was also identified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466530
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 66
    Electronic Resource
    Electronic Resource
    Retention study on silica gel in high-temperature liquid chromatography (HTLC) (1998)
    Springer
    Chromatographia 47 (1998), S. 278-284 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; High-temperature columns ; Retention behavior ; Column equilibration ; Bilayer formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention volumes (V N) of different kinds of test compound have been measured on silica gel as a function of column temperature (T) in the range 20 to 210°C.n-Heptane and mixtures ofn-heptane and polar modifiers were used as mobile phases. With nC7 and nC7-1,4-dioxane mixtures, there was a good linear relationship between InV N and 1/T for column temperatures above 100 °C. When more polar modifiers such as butanol, ethanol and acetic acid were used, ‘N’-shaped curves were obtained for the plots of InV N against 1/T. Possible explanations of this retention behavior have been proposed on the basis of related studies and common physical chemistry relationships. Column equilibration time after alteration of water content or column temperature is greatly reduced at elevated temperatures. This will benefit the application of LSC on silica gel.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466532
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 67
    Electronic Resource
    Electronic Resource
    Use of short columns and high flow rates for rapid gradient reversed-phase chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 291-298 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary electrochromatography ; Rapid analysis ; Short columns ; Rapid gradients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Rapid analyses were performed using reversed-phase liquid chromatography with short (20–100 mm) columns swept by fast yet shallow gradients, and the results compared with those obtained with 150 mm columns and slow gradients. The resolution losses incurred with shorter columns were minimised by employing elevated flow rates, to ensure that comparable mean retention factors were experienced by individual analytes during gradients run on different columns. This conserves gradient steepness. High quality performance was obtained with turn-around times of 5–10 minutes. An overall 5-fold enhancement in the rate of information generation was obtained. The relevance of instrumental parameters and of column and packing dimensions, upon the potential for improved performance is discussed. Some implications for the rapidly developing technique of capillary electrochromatography are briefly indicated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466534
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 68
    Electronic Resource
    Electronic Resource
    Characterization of the precolumn bio trap 500 C18 for direct injection of plasma samples in a column-switching system (1998)
    Springer
    Chromatographia 47 (1998), S. 299-304 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Plasma samples ; Direct injection ; Restricted-access media ; Column-switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new restricted access media (RAM) type of precolumn, Bio Trap 500 C18, for direct injection of plasma samples in column-switching systems was evaluated with respect to the elution of plasma proteins in different mobile phases, the loading capacity of plasma samples, the chromatographic behavior during plasma injections and protein contamination of the packing and sealings. More than 95% of plasma proteins could be excluded from the precolumn within three minutes for all selected mobile phases. Quantitative analyte recoveries could be obtained by injecting plasma samples ranging from 5 to 500 μL with the analyte mass〉150 ng onto a BioTrap 500 C18 column (20×4 mm I.D.). One precolumn tolerated about 15 mL of plasma injection without out noticeable change in retention and pressure. Clogging of the precolumn was encountered (≥45 mL of plasma) due mainly to the adsorption of proteins on the packing. The performance of the analytical column (Kromasil C18) was also examined. The column efficiency decreased by 60% after processing 45 mL plasma in total.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466535
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 69
    Electronic Resource
    Electronic Resource
    Correlation between the chromatographic poperties of silica phenyl packing materials and the retention behaviour of methylated β-cyclodextrins (1998)
    Springer
    Chromatographia 47 (1998), S. 383-390 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Stationary phase characterization ; Silica packing materials ; Cyclodextrins ; Partially methylated β-cyclodextrins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic properties of five columns packed with phenyl-bonded phases were characterized by an approach based on Tanaka's method for column to column comparisons in order to develop an LC analysis of partially methylated β-cyclodextrins. The retention behaviour of β-cyclodextrin, heptakis(2,6-di-O-methyl)-β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin was examined in order to evaluate the different interactions between phenyl stationary phase and this family of compound. Chromatograms show that the residual silanol activity of the packing materials plays a beneficial role in the partially methylated β-cyclodextrins separation process. It is concluded that knowledge of the interactions involved allows one to make a reasoned choice of the stationary phase in order to obtain the best possible analysis of three different commercial samples of partially methylated β-cyclodextrins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466468
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 70
    Electronic Resource
    Electronic Resource
    The preparative chromatographic enantioseparation of a racemic morphanthridine analog on a chiral stationary phase (1998)
    Springer
    Chromatographia 47 (1998), S. 440-442 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separations ; Chiral stationary phase ; Enantiomer separation ; Morphanthridine analog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparative chromatographic enantioseparation of a chiral morphoanthridine analog has been performed on an analytical column using amylose-tris(3,5-dimethylphenylcarbamate) as chiral stationary phase. The racemate (100 mg) was resolved to baseline within 15 min. This paper describes the development of the method, estimation of the capacity of the chiral stationary phase and discussed the potential of the chromatography if performed under preparative conditions. From the results and calculations presented it seems likely that the resolution of 70 tons year−1 could easily be achieved on 30 kg of stationary phase with a mobile-phase consumption of only 720 L day−1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466476
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 71
    Electronic Resource
    Electronic Resource
    Highly selective antibody-mediated extraction of isoproturon from complex matrices (1998)
    Springer
    Chromatographia 47 (1998), S. 453-456 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Affinity chromatography ; Selectivity and capacity ; Isoproturon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the analysis of pesticides such as isoproturon in complex matrices the rate determining step is sample preparation. A novel solid-phase extraction system for isoproturon based on antibody mediated extraction has been developed. The isoproturon can be retained while the immuno-extraction column is washed with phosphate buffered saline and eluted using phosphate buffered saline/ethanol at low pH. The column can preconcentrate isoproturon from up to at least 1000 mL water and elute in 1 mL. Quantitative recovery of isoproturon from water, plasma and urine can be obtained and the proposed water assay can detect as low as 50 ng L−1 with a 50 mL sample, or 5 ng L−1 with a 1 L sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466480
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 72
    Electronic Resource
    Electronic Resource
    HPLC analysis of basic organic compounds in a multi-component ion-interaction system: A mechanistic study (1998)
    Springer
    Chromatographia 47 (1998), S. 493-500 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-interaction chromatography ; Basic organic compounds ; Diamine modifiers ; Retention mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase HPLC separations of basic compounds have been optimized by use of mobile phases containing 1,8-diaminooctane (DAO) as amine modifier and heptanesulfonate as counter-ion. Such studies have demonstrated the high resolution and selectivity of this chromatographic system compared with mobile phases prepared with the more widely used primary amines. With the aim of clarifying the retention mechanism involved, three sets of compounds with different structures and properties were analyzed: sulfamidics and trimethoprim, aromatic diamines and aminophenols, and a standard mixture of lipophilic basic drugs. The conditions investigated were: diaminoalkane modifier concentration, diaminoalkane modifier alkyl-chain length, nature and concentration of the counter-ion, pH of the mobile phase, concentration of the organic modifer, and the nature of the stationary phase as characterized by percentage carbon loading. Analysis of chromatographic behavior as a function of the chromatographic conditions has enabled the proposal of a mechanism of retention of the three classes of compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467485
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 73
    Electronic Resource
    Electronic Resource
    Liquid chromatography of polymer mixtures by a combination of exclusion and full adsorption mechanisms. Three- and four-component polymer blends (1998)
    Springer
    Chromatographia 48 (1998), S. 65-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Multicomponent mixtures ; Separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coupling of full adsorption-desorption and size-exclusion chromatography (FAD-SEC) has been applied to the separation and molecular characterization of three- and four-component polymer blends. The method is based on the full adsorption of alln orn−1 components of the polymer blend in a specially designed FAD minicolumn. By appropriate eluent switching the adsorbed polymers are desorbed stepwise from the FAD minicolumn into an on-line SEC column for molecular characterization. It is shown that the desorption isotherms of particular blend components give valuable information about the appropriate displacer composition. The exact position of the desorption isotherms depends, however, both on the amount of polymer adsorbed and in the presence of other, chemically different, polymers within FAD column. The nature and composition of the displacer must, therfore, be adjusted if the intervals between the desorption of particular blend components are to be large enough to prevent displacement overlap.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467518
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 74
    Electronic Resource
    Electronic Resource
    Characterisation of pitch by HPLC (1998)
    Springer
    Chromatographia 47 (1998), S. 373-382 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyaromatic hydrocarbons ; Pitch
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new high performance liquid chromatography method for the characterisation of toluene-soluble fractions of pitches has been developed. Although a chromatographic system typical of size exclusion chromatography was used, results indicate that, for these structurally complex samples, separation does not follow the usual discrimination by molecular size. A differentiation between several classes of polyaromatic hydrocarbons is achieved instead. Data are reported on the analysis of individual standard polyaromatic hydrocarbons, showing that four different elution ranges can be observed: three ofcata-condensed compounds (Cata1, Cata2 and Cata3) and one ofperi-condensed compounds (Peri). Results are reported proving the capacity of this high performance liquid chromatography method to distinguish between pitches of different origin and nature. It is also effective for the study of the chemical reactions occurring during heat treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466467
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 75
    Electronic Resource
    Electronic Resource
    Aminopropyl-silica as an advantageous alternative to nonpolar sorbents for continuous cleanup/preconcentration of vitamin D3 metabolites (1998)
    Springer
    Chromatographia 47 (1998), S. 367-372 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aminopropyl-silica sorbent ; Continuous cleanup/preconcentration ; Hydroxyvitamin D3 metabolites ; Flow injection analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new procedure for continuous cleanup and concentration of hydroxyvitamin D3 metabolites prior to their separation by HPLC and UV-detection is reported. The process is based on the use of aminopropyl-silica as solid-phase sorbent as an alternative to the use of nonpolar sorbents. The improvement thus achieved has been tested by comparing the results with those obtained using octadecyl-C18 as non-polar sorbent. The comparison has been based on the calibration graphs (linear range, detection and quantitation limits), precision and multiple standard addition method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466466
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 76
    Electronic Resource
    Electronic Resource
    Analysis of anka pigments by liquid chromatography with diode array detection and tandem mass spectrometry (1998)
    Springer
    Chromatographia 47 (1998), S. 529-536 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin layer chromatography ; Mass spectrometry detection ; Anka pigments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Anka is withMonascus sp. fermented rice, which shows a purplish red color. On rice grainsMonascus purpureus DSM 1379 synthesized four anka pigments. Through extraction of anka with n-hexane and methanol in succession and through repeated crystallizations from absolute ethanol anka pigments were crystallized into two fractions: organge anka pigments (rubropunctatin and monascorubrin) and yellow anka pigments (monascin and ankaflavin). The treatment of two organge anka pigments with aqueous ammonia solution gave red nitrogen analogues (rubropunctatamine and monascorubramine). The above six pigments were separated into each pigment by two dimensional thin layer chromatography (TLC) or high performance liquid chromatography (HPLC). HPLC-atmospheric pressure chemical ionization-tandem mass spectrometry (HPLC-APCI-MS-MS) and direct probe mass spectrometry (MS) were used to identify these pigments. HPLC-diode array detector (HPLC-DAD) was used to determine UV-VIS spectra of pigments. Pigments were analyzed with HPLC under the following conditions: C18 column, acetonitrile/water (80∶20, v/v), 0.5 mL min−1, 233 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467490
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 77
    Electronic Resource
    Electronic Resource
    Problems in the analysis of propofol in blood when protein precipitation is used in sample preparation (1998)
    Springer
    Chromatographia 47 (1998), S. 523-528 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Propofol in blood ; Precipitation procedure ; Drug co-precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Propofol (2,6-diisopropylphenol) is one of a group of intravenously administered hypnotic agents enabling easy inducement of sleep. Increasingly wider application of this drug in anaesthesiology has led to increasing demands for its precise and reliable analysis in the physiological fluids and tissues of man. The identification of problems in the determination of propofol seems to be essential. This paper deals with difficulties of propofol analysis in blood by HPLC when protein precipitation is used in sample preparation. The data obtained show that introduction of large amounts of fluids (for example electrolytes or blood-substitutes) into the blood, for example during long surgical operations, can significantly influence the results from propofol analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467489
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 78
    Electronic Resource
    Electronic Resource
    HPLC determination of colistin and aminoglycoside antibiotics in feeds by post-column derivatization and fluorescence detection (1998)
    Springer
    Chromatographia 48 (1998), S. 32-36 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Post-column derivatization ; Feeds ; Aminoglycoside antibiotics ; Colistin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase, HPLC methods employing post-column derivatization and fluorescence detection were developed for the determination of the peptide colistin and four aminoglycoside antibiotics in feeds. Extraction of the analytes was by sonication and shaking with dilute hydrochloric acid. Post-column derivatization was performed using orthophtaldialdehyde-2-mercaptoethanol chemistry. Assay of colistin was by using an acetonitrile-aqueous sodium sulphate-triethylammonium phosphate (pH 2.8) eluent. Aminoglycoside antibiotics:amikacin, kanamycin, gentamycin and neomycin were analyzed using a tetrahydrofuran-aqueous sodium sulphate-sodium pentanesulphonate-acetic acid mobile phase. The method was also applied to some pharmaceutical preparations. Preliminary results showed that the method can be adapted for the assay of the above antibiotics in meat and animal serum for residue and pharmacokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467512
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 79
    Electronic Resource
    Electronic Resource
    High-Performance liquid chromatographic determination of dibromomannitol in plasma (1998)
    Springer
    Chromatographia 48 (1998), S. 17-19 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dibromomannitol in plasma ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Myelobromol 1,6-dibromo-1,6-dideoxy-D-mannitol (dibromomannitol, DBM) is a bifunctional alkylating agent that has been in clinical use since 1963. It is currently included at high dose in preconditioning regimen for bone marrow transplantation (BMT) and is a main-stay of treatment for polycythaemia vera. A high-performance liquid chromatographic method was developed for the determination of DBM in the plasma. The basis of the assay is a derivatization with sodium-diethyldithiocarbamate at 42°C in the presence of 1-bromo-1-deoxy-3,6-anhydro-galactitol as internal standard (IS). The analysis was carried out on a 250×4mm Hypersil 5 CPS column equipped with a 20×4 mm Hypersil 10 CPS precolumn. The eluent consisted of heptane:isopropyl-alcohol: glacial acetic acid=600:76:80 w/w. The flow rate was 1.2 mL min−1. UV detection was performed at 254 nm. The calibration graph was linear in the concentration range of 2.5–260 μM of DBM in plasma. The limit of detection was 1.0 μM. The precision and accuracy of the method was between the good laboratory practice (GLP) required limits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467509
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 80
    Electronic Resource
    Electronic Resource
    Enantiomeric separation of unusual secondary aromatic amino acids (1998)
    Springer
    Chromatographia 48 (1998), S. 53-58 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Enantiomeric separation ; Chiral derivatization ; Unusual secondary aromatic amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic and gas chromatographic methods were developed for the separation of unusual secondary aromatic amino acids. Amino acids containing 1,2,3,4-tetrahydroisoquinoline, 1,2,3,4-tetrahydronorharmane-1-carboxylic acid and 1,2,3,4-tetrahydro-3-carboxy-2-carboline moieties were synthetized in racemic or chiral forms. The high-performance liquid chromatography was carried out either on a teicoplanin-containing chiral stationary phase or on an achiral C18 column. In the latter case the diastereomers of the amino acids formed by precolumn derivatization with the chiral reagents 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl isothiocyanate or 1-fluoro-2,4-dinitrophenyl-5-L-alanine amide were separated. The gas chromatographic analyses were based on separation on a Chirasil-L-Val column.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467516
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 81
    Electronic Resource
    Electronic Resource
    HPLC separation of hydrogenated derivatives of buckminsterfullerene (1998)
    Springer
    Chromatographia 48 (1998), S. 59-64 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Buckminsterfullerene ; Hydrogenation ; Separation technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of composition and flow rate of the mobile phase on the HPLC separation of hydrogenated buckminsterfullerene (C60Hn n=2–38) was investigated on BuckySep column. Toluene was used as the basic solvent and hexane, heptane, cyclohexane, THF, acetonitrile, acetone, ethanol and 2-propanol as co-solvents. The fraction of co-solvents was varied 10–80%, and the flow rate 1–0.1 mL min−1. Toluene-acetonitrile 65∶35 and toluene-acetone 50∶50 provided the best separation. Under the best conditions complete separation of C60H2 and almost complete separation of the four most abundant isomers of C60H4 were achieved. Separation of derivatives with higher hydrogen content was very poor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467517
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 82
    Electronic Resource
    Electronic Resource
    Development of an Ion-pair HPLC method for the determination of 2,4- and 2,6-toluendiamine in human plasma (1998)
    Springer
    Chromatographia 47 (1998), S. 84-88 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair LC ; Plasma ; 2,4-Toluendiamine ; 2,6-Toluendiamine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An ion-pair HPLC method is presented for the determination in plasma of 2,4- and 2,6-toluendiamine (TDA), known carcinogens. The chromatographic conditions consisted in isocratic elution on a reversed phase C18 column with 5 mM octanesulfonic acid in methanol-water, 45∶55, as mobile phase. UV detection was performed at 235 nm. Samples were analyzed after a simple single step liquid-liquid extraction and the method was validated by measurement of precision (interassay and intraassay), sensitivity, specificity, linearity, and recovery. The detection limit for both TDAs in plasma was 20 ng mL−1. The correlation coefficients based on the intrassay calibration curve were 0.998 and 0.997 for 2,6- and 2,4-TDA, respectively. The intraassay accuracy, expressed in terms of recovery, was found to be up to 89.91% and 97.05% for 2,6- and 2,4-TDA, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466791
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 83
    Electronic Resource
    Electronic Resource
    Ligand-exchange chromatographic separation of DL-amino acids on aminopropylsilica-bonded chirals-triazines (1998)
    Springer
    Chromatographia 47 (1998), S. 637-642 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange chromatography ; Chiral stationary phases ; Enantiomer separation ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chiral stationary phases (CSPs) were synthesized by reaction of aminopropylsilica (APS) with chiral monochloro-s-triazines (MCTs). MCTs were obtained by reaction of 2,4,6-trichloro-s-triazine (cyanuric chloride) with one equivalent of methanol and, subsequently, with one equivalent of L-prolinetert butyl ester (H-Pro-OtBu) orN-tert butyloxycarbonyl-L-lysinetert butyl ester (Boc-Lys-OtBu). End-capping of unreacted amino groups of APS with acetic anhydride, followed by trifluoroacetolytic cleavage of the protecting groups of amino acids (AAs), afforded two chiral stationary phases bearing either L-proline (CSP-3) or L-lysine (CSP-4) as chiral selector. Using ligand-exchange chromatography matography with addition of Cu2+ to the mobile phase, enantiomers of free DL-AAs and a fewN-(2,4-dinitrophenyl)-DL-AAs were separated on CSP-3, whereasN-(dansyl)-DL-AAs were separated on CSP-4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467446
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 84
    Electronic Resource
    Electronic Resource
    Study of the influence of electronic effects on the retention of substitutedN-benzylideneanilines in normal-phase liquid chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 164-170 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; N-Benzylideneanilines ; Hierarchical ascending classification ; Correspondence factor analysis ; Electronic effects ; Quantitative structure-retention relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A series of 72 substitutedN-benzylideneanilines (NBA) has been studied by normal-phase liquid chromatography by use of an experimental design based on variation of the composition of mobile phases prepared from heptane and three modifiers, tetrahydrofuran, 1-octanol and ethyl acetate, for each of which the specific interactions are different. Seven mobile phases were defined in the experimental design. The chromatographic data obtained are used to discuss the behavior of NBA by application of complementary chemometric methods—hierarchical ascending classification (HAC) and correspondence factor analysis (CFA). Although solute polarity has the greatest effect on retention, construction of HAC and CFA plots shows that solute behavior is also influenced by second-order electronic effects arising as a result of specific interactions between the solutes and the different modifier solvents. A quantitative structure-retention relationship has been established between Hammett's constants and the solutes projection on the first factorial axis of CFA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466576
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 85
    Electronic Resource
    Electronic Resource
    The use of mobile phase pH and column temperature to reverse the retention order of enantiomers on chiral-AGP® (1998)
    Springer
    Chromatographia 47 (1998), S. 189-196 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Experimental design ; Mosapride ; Reversal of retention order ; Effect of pH and column temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Enantiomeric separation of mosapride and a structurally related compound was performed using chiral chromatography and experimental design. Unique effects of mobile phase pH and column temperature made it possible to control the elution order of the enantiomers when using Chiral-AGP as the solid phase. At a low mobile phase pH (〈6) the (R)-enantiomer of mosapride elutes before the (S)-form whereas the (S)-enantiomer elutes first at a high mobile phase pH (〉6). By using a mobile phase pH around 6, the column temperature could also be used to control the elution order of the enantiomers of mosapride. Similar effects of mobile phase pH and column temperature were obtained for the enantiomers of a structurally related compound, a metabolite (M1). Isocratic chromatographic systems made it possible to determine enantiomeric impurities less than 0.1% in the respective enantiomer of mosapride. The enantiomers of mosapride as well as the enantiomers of M1 could easily be separated simultaneously using Chiral-AGP and a simple gradient elution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466580
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 86
    Electronic Resource
    Electronic Resource
    Enantiomeric separation of four methylenedioxylated amphetamines on β-cyclodextrin chiral stationary phases (1998)
    Springer
    Chromatographia 47 (1998), S. 285-290 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantiomeric separation ; β-Cyclodextrins ; Methylenedioxylated amphetamines ; Ecstasy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Native and derivatized β-cyclodextrins such as chiral stationary phases (CSP) were used for the simultaneous enantiomeric separation of four methylenedioxylated amphetamines (MDA, MDMA, MDEA and MBDB) by liquid chromatography. Fluorimetric detection was used in order to enhance sensitivity and selectivity. The mobile phase was, optimised by studying the influence of pH, triethylamine concentration, organic solvent type, column temperature and flow rate of the mobile phase. This method was validated by determining linearity, precision, accuracy, limits of detection and quantification, and was applied to the stereoselective analysis of illicit tablets (23 samples) and of human whole blood samples (spiked samples and two post-mortem cases). Whereas no significant deviation from a racemic ratio was observed in the tablets contents, the analysis of blood samples showed an enantioselective metabolism of MDMA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466533
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 87
    Electronic Resource
    Electronic Resource
    Simultaneous determination of 3,4-dihydroxymandelic acid, 4-hydroxy-3-methoxymandelic acid, 3,4-dihydroxyphenylglycol, 4-hydroxy-3-methoxyphenylglycol, and their precursors, in human urine by HPLC with electrochemical detection (1998)
    Springer
    Chromatographia 47 (1998), S. 396-400 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Coulometric detection ; Mandelic acids ; Phenylglycols ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the quantification of urinary 3,4-dihydroxymandelic acid (DOMA), 4-hydroxy-3-methoxymandelic acid (VMA), 3,4-dihydroxyphenylglycol (DHPG), and 4-hydroxy-3-methoxyphenyglycol (MHPG). Separation and determination of these compounds in biological samples was previously thought to be very difficult. In this work the separation has been achieved by reversed-phase high-performance liquid chromatography with step-wise gradient elution with three mobile phases. The conditions for coulometric detection have been optimized for effective determination of these compounds. In analysis of a sample of human urine, after a simple deproteinization proceudre, DOMA, VMA, DHPG, and MHPG were separated from interferences and quantified successfully; the average levels of these compounds in six different samples were 33.87±1.03, 1202±41.3, 31.3±1.92, and 80.6±2.15 μg (24 h)−1, respectively. Their precursors E, MN, DOPA, DA, NE, DOPAC, HVA, 3MT, and NMN, and the indolamine 5HT and its metabolite 5HIAA (a list of abbreviations is given at the end of the paper) can also be determined simultaneously in the same chromatographic run. The overlapping peak of DHPG was resolved by deconvolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466470
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 88
    Electronic Resource
    Electronic Resource
    Optimization of solvent selectivity for the chromatographic separation of fat-soluble vitamins using a mixture-design statistical technique (1998)
    Springer
    Chromatographia 47 (1998), S. 401-412 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optimization ; Mixture design ; Special cubic polynomial model ; Pareto-optimality ; Overlapping resolution mapping (ORM)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A systematic approach, using a mixture-design statistical technique, has been developed for selecting the optimum mobile phase for the separation of fat-soluble vitamins in reversed-phase high-performance liquid chromatography. A quaternary mixture of methanol, acetonitrile, tetrahydrofuran and water was used as mobile phase. Retention time and peak width were recorded in ten runs augmented with five replicates and the data were subsequently fitted to special cubic polynomial models. The resulting mathematical equations enabled prediction of resolution over the entire parameter space. Contour plots of minimum effective resolution and maximum retention time as a function of mobile phase composition are presented and discussed. Visual inspection of these plots provides an overview of the quality of the separation and the analysis time required for each possible mobile-phase composition with n the parameter space. It is demonstrated that the methodology followed was an important tool which enabled the taking of informed decisions necessary for selection of the optimum mobile phase for a chromatographic separation. A combination ofR S minimum andt R maximum as optimization criteria in a multicriteria decision-making plot using pareto-optimality concept is discussed. This combination enabled visual demonstration of the compromise between separation quality and the economics of analysis time. Our methodology has been compared with the common used technique of ‘overlapping resolution mapping’.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466471
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 89
    Electronic Resource
    Electronic Resource
    Applications of molecularly imprinted materials as selective adsorbents: Emphasis on enzymatic equilibrium shifting and library screening (1998)
    Springer
    Chromatographia 47 (1998), S. 465-469 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Affinity chromatography ; Molecular imprinting ; Molecular recognition ; Combinatorial libraries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular imprinting is an attractive method for producing highly selective adsorbents, and several new and potentially useful applications based on molecularly imprinted polymers (MIPs) have been described in recent years. In this article, we highlight some of the areas where these materials have found application, and also describe some new fields of application where the selectivities of imprinted materials can be gainfully employed, for example as binding matrices in the screening of combinatorial libraries, and as auxiliary agents in enzymatic syntheses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466482
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 90
    Electronic Resource
    Electronic Resource
    On-line monitoring of monosaccharides and ethanol during a fermentation by microdialysis sampling, liquid chromatography and two amperometric biosensors (1998)
    Springer
    Chromatographia 47 (1998), S. 501-508 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fermentation ; Microdialysis sampling ; Monosaccharides and ethanol ; On-line monitoring ; Biosensors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two amperometric biosensors were used as detection units in liquid chromatography for on-line monitoring of the production of fuel ethanol during a fermentation. Sampling was performed with a microdialysis probe, and the dialysate was introduced into a liquid chromatographic system providing separation of the substrates and the product: three monosaccharides and ethanol. The analytes were detected by two carbon paste electrodes based on pyranose oxidase and alcohol oxidase, respectively, co-immobilised with horseradish peroxidase, operating in parallel at −50 mVvs. Ag/AgCl. The measured linear ranges of the biosensors by direct injection into the LC system were for glucose 0.3–2.5 g L−1, xylose 0.5–6.7 g L−1, galactose 0.5–6.7 g L−1, and ethanol 1.6–11.7 g L−1, respectively. Injection of standard solutions were required to monitor the stability of the biosensors. Due to the strict selectivity of the biosensors, no interference from other compounds in the broth was encountered from other compounds in the broth was encountered in the quantification. The fermentation process was monitored for 16 h. The on-line results were compared with off-line measurements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467486
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 91
    Electronic Resource
    Electronic Resource
    Porous copolymer of the methacrylic ester of dihydroxydiphenylmethane diglycidyl ether and divinylbenzene as an HPLC packing (1998)
    Springer
    Chromatographia 47 (1998), S. 509-514 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous copolymers with hydroxyl groups ; Chemical modification of phases ; Selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Dimethyldichlorosilane has been used to deactivate the hydroxyl groups present in the skeleton of the porous polymer formed from the methacrylic ester ofp, p′-dihydroxydiphenylmethane diglycidyl ether and divinylbenzene. The influence of chemical modification of the copolymer on its chromatographic behavior has been studied. The retention indices of five homologous series and test compounds were calculated to determine the selectivity of the packings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467487
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 92
    Electronic Resource
    Electronic Resource
    Determination of nalbuphine hydrochloride, methylparaben, and propylparaben in nalbuphine hydrochloride injection by high performance liquid chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 515-522 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 4,5-Epoxymorphinan ; Nalbuphine hydrochloride injection ; Stability assays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A stability-indicating liquid chromatographic method has been developed for the determination of nalbuphine hydrochloride, methylparaben, and propylparaben in nalbuphine hydrochloride injection. Reversed-phase chromatography was carried out using a mobile phase containing 0.05 % trifuoroacetic acid, acetonitrile, and tetrahydrofuran. Quantitation was achieved with UV detection at 280 nm. Validation data for linearity, accuracy, precision, specificity, and robustness are presented. The chromatographic system resolves nalbuphine from synthetic impurities and degradation products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467488
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 93
    Electronic Resource
    Electronic Resource
    Determination of triacylglycerol composition of idiazabal cheese (1998)
    Springer
    Chromatographia 47 (1998), S. 579-586 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Ewe's cheese ; Triacylglycerols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Triacylglycerols from Idiazabal cheese fat were analysed by high-performance liquid chromatography (LC) with a non-linear gradient of acetone in acetonitrile and a light-scattering detector. Molecular species of triacylglycerols were predicted by a simple and a multiple linear regression analysis of logk of the LC peaks and molecular variables such as equivalent carbon number of the possible triacylglycerol, chain length and number of double bonds of each fatty acid of the triacylglycerol. Predicted results were confirmed by gas chromatographic analysis of the fatty acids in the LC peaks. The main triacylglycerols of Idiazabal cheese fat contained butyric acid, butyroyl-dipalmitin, butyroyl-myristoyl-palmitin and butyroyl-palmitoyl-olein. The most abundant triacylglycerols were those with even partition numbers of 36, 34 and 38.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467499
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 94
    Electronic Resource
    Electronic Resource
    High-Performance liquid chromatographic separation of enantiomers of unusual amino acids possessing cycloalkane or cycloalkene skeletons on a chiral crown ether containing stationary phase (1998)
    Springer
    Chromatographia 48 (1998), S. 20-26 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Crownpak CR(+) Column ; Cyclic β-Amino Acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Direct reversed-phase high-performance liquid chromatographic methods were developed for the separation and identification of the enantiomers of mono- and bicyclic racemic β-amino acids:cis- andtrans-2-aminocyclopentane-1-carboxylic acids,cis- andtrans-2-aminocyclohexane-1-carboxylic acids,cis- andtrans-2-amino-4-cyclohexene-1-carboxylic acids,diendo- anddiexo-3-aminobicyclo[2.2.1]heptane-2-carboxylic acids anddiendo- anddiexo-3-amino-5-bicyclo[2.2.1]heptene-2-carboxylic acids. Enantioseparation was carried out by the application of a chiral stationary phase, Crownpak CR(+). The conditions of separation were optimized by changing the temperature, the flow rate and the pH of the mobile phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467510
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 95
    Electronic Resource
    Electronic Resource
    Isolation and characterization of 3,5,6-trihydroxy-carotenoids from petals ofLilium tigrinum (1998)
    Springer
    Chromatographia 48 (1998), S. 27-31 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Lilium tigrinum ; Carotenoids ; Xanthins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reinvestigation by HPLC of the petals ofLilium tigrinum and the isolation of some minor compounds is reported. Using HPLC-controlled, preparative-column chromatography, 5,6-diakarpoxanthin (6), 6-epikarpoxanthin (2), 5,6-diacapsokarpoxanthin (8), and 9Z-antheraxanthin (9Z-13) were isolated and characterized. Based on spectroscopic data the absolute configurations of6 and8 were identical with those originating from paprika, thus the 5,6-diakarpoxanthin (6) and 5,6-diacapsokarpoxanthin (8) have the 3S, 5S, 6S configuration and 6-epikarpoxanthin (2) has the 3S, 5R, 6S configuration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467511
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 96
    Electronic Resource
    Electronic Resource
    Monitoring of biologically active amines in cereals and cereal based food products by HPLC (1998)
    Springer
    Chromatographia 48 (1998), S. 37-42 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biologically active amines ; Polyamines ; Cereal and Cereal products
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Biologically active amines (putreanine sulphate, N-acetyl putrescine, putrescine, cadaverine, histamine, agmatine, N-acetyl spermidine, spermidine, spermine) were separated and quantified in cereal flour and cereal products by a liquid chromatographic method. The method consists of the separation of ion pairs formed between biologically active amines and octanesulphonic acid on a reversed-phase column, postcolumn derivatization with o-phtalaldehyde-2-mercapthoethanol and spectrofluorometric detection. Results of the reliability study were satisfactory. The method was linear for each amine at 1–10 mg L−1. Putrescine and spermidine were the only amines always detected in cereal flour and cereal products, ranging from 2.45 to 47.83 mg kg−1 for putrescine and 3.27 to 37.14 mg kg−1 for spermidine. The most important differences among types of samples were found in polyamine derivatives.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467513
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 97
    Electronic Resource
    Electronic Resource
    An improved method for assay of vitamin C in fish feed and tissues (1998)
    Springer
    Chromatographia 48 (1998), S. 43-47 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vitamin C analysis ; Ascorbate-2-phosphate and sulphate esters ; Enzyme shifting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method was devised to assay four forms of vitamin C: L-ascorbic acid (AA), dehydroascorbic acid (DHA), ascorbate-2-mono- and polyphosphate (AMP, APP), as well as ascorbate-2-monosulphate (AMS), in sample series of different fish tissues and feed. Direct and indirect detection were combined. Sample extractions were carried out with 0.2 mol L−1 sodium acetate buffer (pH 4.8) and extracts were deproteinized after different chemical or enzymatic reactions, with perchloric acid. The DHA was reduced to AA with dithioerythritol (DTE). Ascorbate oxidase enzyme was used for the detection of background and an acidic phosphatase enzyme for the hydrolysis of different phosphate esters. Ascorbate-2-sulphate was detected directly with help of coinjection of the compound. Chromatographic analysis was carried out with a single column isocratic reverse phase method. The mobile phase was an aqueous buffer of 0.04 M sodium-acetate, 0.05 mM EDTA, 0.5 mM tetrabutylammonium dihydrogen phosphate (TBA) adjusted to pH 3.76 with 85% H3PO4 and with 24 mL methanol added to 1000 mL. C-18 columns were used with 0.6 mL min−1 flow rate at 23°C. The vitamin C forms were detected by UV absorption at 250 nm. The determination limit was 1.0–5.0 μg g−1 in AA equivalent. The standard deviations were between 1–6% and depended on the concentrations of vitamin C forms and tissues. Recoveries were between 90–96% in samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467514
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 98
    Electronic Resource
    Electronic Resource
    Comparative study on determination of fumagillin in fish by normal and reversed phase chromatography (1998)
    Springer
    Chromatographia 48 (1998), S. 48-52 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal- and reversed-phase LC ; Fumagillin in fish samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fumagillin is an antibiotic agent mostly used in the veterinary profession. A normal-phase liquid chromatographic method was developed for the determination of this drug in fish matrices. A hexane-dichloromethanedioxan-2-PrOH-acetic acid (43:43:9:5:0.1 v/v %) eluent was used on a Perkin Elmer silica gel column. For validation of the process a reversed-phase HPLC method was also developed (eluent: acetonitrile-water-bicyclohyxylamine 70:30:0.05 v/v %, with Spherisorb ODS, as stationary phase). Recovery is about 100% and the limit of detection is 5 ng g−1 for meat samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467515
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 99
    Electronic Resource
    Electronic Resource
    Rapid determination of ranitidine in human plasma by high-performance liquid chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 391-395 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ranitidine ; Plasma ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method has been developed for the quantification of rantidine in plasma for pharmacokinetic studies. Metoclopramide was used as internal standard. The method uses a simple and rapid sample clean-up procedure involving single-step extraction with organic solvent to extract ranitidine from plasma. After evaporation and reconstitution the samples are chromatographed on a 250 mm×4 mm base-stable reversed-phase column with 0.05 M ammonium acetate-acetonitrile, 75∶25 (v/v) as mobile phase and UV detection at 313 nm. The calibration graph was linear for quantities of ranitidine between 10 and 2000 ng mL−1. Intra- and inter-dayCV did not exceed 11.64%. The quantitation limit was 10 ng mL−1 for human plasma. The applicability of this method for pharmacokinetic studies of ranitidine after oral administration are described. Approximately 90 samples can be processed in 24 h.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466469
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 100
    Electronic Resource
    Electronic Resource
    An improved extraction of marrubiim fromMarrubium vulgare (1998)
    Springer
    Chromatographia 47 (1998), S. 449-450 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chitin stationary phase ; Marrubiin ; Analgesic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Marrubiin is the main active compound isolated fromM. vulgare, a medicinal plant used in folk medicine to cure several diseases. The present study shows that chitin, an abundant natural polymer, may be successfully in chromatography column to separate marrubiin from complex mixtures. The experimental procedure described here represents an efficient and rapid method to obtain such compound in high yield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466478
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...